Heat resistant aerogel materials

ABSTRACT

The present disclosure provides an aerogel composition which is durable and easy to handle, which has favorable performance in aqueous environments, and which also has favorable combustion and self-heating properties. Also provided is a method of preparing an aerogel composition which is durable and easy to handle, which has favorable performance in aqueous environments, and which has favorable combustion and self-heating properties. Further provided is a method of improving the hydrophobicity, the liquid water uptake, the heat of combustion, or the onset of thermal decomposition temperature of an aerogel composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This nonprovisional application is a continuation of U.S. Nonprovisionalpatent application Ser. No. 16/298,212, entitled “Hydrophobic AerogelMaterials”, filed Mar. 11, 2019; U.S. Nonprovisional patent applicationSer. No. 15/835,005, entitled “Hydrophobic Aerogel Materials”, filedDec. 7, 2017; U.S. Nonprovisional patent application Ser. No.15/835,136, entitled “Hydrophobic Aerogel Materials”, filed Dec. 7,2017, now U.S. Pat. No. 10,233,302; U.S. Nonprovisional patentapplication Ser. No. 15/835,190, entitled “Hydrophobic AerogelMaterials”, filed Dec. 7, 2017, now U.S. Pat. No. 10,227,472; U.S.Nonprovisional patent application Ser. No. 15/835,258, entitled“Hydrophobic Aerogel Materials”, filed Dec. 7, 2017, now U.S. Pat. No.10,233,303; each of which is a continuation of U.S. Nonprovisionalpatent application Ser. No. 14/873,753, entitled “Hydrophobic AerogelMaterials”, filed Oct. 2, 2015, now U.S. Pat. No. 9,868,843; whichclaims priority to U.S. Provisional Application No. 62/059,555, entitled“Hydrophobic Aerogel Materials”, filed Oct. 3, 2014 and to U.S.Provisional Application No. 62/118,864, entitled “Hydrophobic AerogelMaterials”, filed Feb. 20, 2015 and to U.S. Provisional Application No.62/232,945, entitled “Hydrophobic Aerogel Materials”, filed Sep. 25,2015; each of which is incorporated herein by reference in its entirety.

BACKGROUND

Low-density aerogel materials are widely considered to be the best solidinsulators available. Aerogels function as insulators primarily byminimizing conduction (low structural density results in tortuous pathfor energy transfer through the solid framework), convection (large porevolumes and very small pore sizes result in minimal convection), andradiation (IR absorbing or scattering dopants are readily dispersedthroughout the aerogel matrix). Aerogels can be used in a broad range ofapplications, including: heating and cooling insulation, acousticsinsulation, electronic dielectrics, aerospace, energy storage andproduction, and filtration. Furthermore, aerogel materials display manyother interesting acoustic, optical, mechanical, and chemical propertiesthat make them abundantly useful in various insulation andnon-insulation applications.

SUMMARY

In one general aspect, the present disclosure can provide aerogelcompositions which are durable and easy to handle, which have favorableperformance in aqueous environments, and which also have favorablecombustion and self-heating properties. In certain embodiments, thepresent disclosure presents aerogel compositions which are reinforcedaerogel compositions that are flexible, resilient, and self-supporting,which have favorable performance in aqueous environments, and which alsohave favorable combustion and self-heating properties.

In another general aspect, the present disclosure can provide aerogelcompositions comprising a silica-based framework, and which have thefollowing properties: a) a density of 0.60 g/cm³ or less; b) a thermalconductivity of 50 mW/m*K or less; and c) a liquid water uptake of 40 wt% or less. In certain embodiments, aerogel compositions of the presentdisclosure have a heat of combustion of less than 717 cal/g. In certainembodiments, aerogel compositions of the present disclosure have anonset of thermal decomposition of hydrophobic organic materialtemperature of between 300° C. and 700° C. In certain embodiments,aerogel compositions of the present disclosure have a density of 0.50g/cm3 or less, 0.40 g/cm3 or less, 0.30 g/cm3 or less, 0.25 g/cm3 orless, or 0.20 g/cm3 or less. In certain embodiments, aerogelcompositions of the present disclosure have a thermal conductivity of 45mW/M*K or less, 40 mW/M*K or less, 35 mW/M*K or less, 30 mW/M*K or less,25 mW/M*K or less, 20 mW/M*K or less, or a thermal conductivity between5 mW/M*K and 50 mW/M*K. In certain embodiments, aerogel compositions ofthe present disclosure have a liquid water uptake of 35 wt % or less, 30wt % or less, 25 wt % or less, 20 wt % or less, 15 wt % or less, or 10wt % or less. In certain embodiments, aerogel compositions of thepresent disclosure have a heat of combustion of 650 cal/g or less, 600cal/g or less, 550 cal/g or less, 500 cal/g or less, 450 cal/g or less,400 cal/g or less, or a heat of combustion between 250 cal/g and 717cal/g. In certain embodiments, aerogel compositions of the presentdisclosure have an onset of thermal decomposition of hydrophobic organicmaterial temperature of 400° C. or higher, 450° C. or higher, 475° C. orhigher, 500° C. or higher, 525° C. or higher, 550° C. or higher, 575° C.or higher, 600° C. or higher, or an onset of thermal decompositiontemperature between 400° C. and 700° C. In a preferred embodiment,aerogel compositions of the present disclosure have the followingproperties: a) a density of 0.40 g/cm³ or less; b) a thermalconductivity of 40 mW/m*K or less; c) a liquid water uptake of 40 wt %or less; d) a heat of combustion between 140 cal/g and 600 cal/g; and e)an onset of thermal decomposition temperature of between 525° C. and700° C. In certain embodiments, aerogel compositions of the presentdisclosure have a ratio of T¹⁻²-T³ silica species of between about 0.01and 0.5, and/or a ratio of Q²⁻³:Q⁴ silica species of between about 0.1and 1.5. In a certain embodiments, aerogel compositions of the presentdisclosure are reinforced aerogel composition, fiber-reinforced aerogelcompositions, or aerogel blanket compositions. In certain embodiments,aerogel compositions of the present disclosure have a hydrophobicorganic content between about 1 wt % and about 30 wt %, between about 1wt % and about 25 wt %, between about 1 wt % and about 20 wt %, betweenabout 1 wt % and about 15 wt %, between about 1 wt % and about 10 wt %,or between about 1 wt % and about 5 wt %.

In another general aspect, the presents disclosure can provide a methodof preparing an aerogel composition, comprising: a) providing aprecursor solution comprising silica gel precursor materials, a solvent,and optionally a catalyst; b) allowing the silica gel precursormaterials in the precursor solution to transition into a gel material orcomposition; c) extracting at least a portion of the solvent from thegel material or composition to obtain an aerogel material orcomposition; d) incorporating at least one hydrophobic-bound siliconinto the aerogel material or composition by one or both of: i) includingin the precursor solution at least one silica gel precursor materialhaving at least one hydrophobic group, or ii) exposing the precursorsolution, gel composition, or aerogel composition to a hydrophobizingagent; and e) heat treating the aerogel material or composition byexposing the aerogel material or composition to a reduced oxygenatmosphere at a temperature above 300° C. In certain embodiments,methods of the present disclosure include exposing the aerogelcomposition to a reduced oxygen atmosphere at temperatures between 300°C. and 650° C. for a period of time between about 30 seconds and about200 minutes to obtain a treated aerogel composition. In certainembodiments, methods of the present disclosure include incorporating areinforcement material into the aerogel composition by combining thereinforcement material with the precursor solution either before orduring the transition of the silica gel precursor materials in theprecursor solution into the gel composition. In a preferred embodiment,the reinforcement material comprises a continuous sheet of fiberreinforcement material. In certain embodiments, methods of the presentdisclosure include the temperature exposure of the heat treatment of theaerogel composition being limited to a temperature below 850° C. Incertain embodiments, methods of the present disclosure include the totaltime period for transitioning the at least one gel precursor in theprecursor solution into a gel material being within a period of 30 hoursor less. In certain embodiments, methods of the present disclosureinclude the reduced oxygen atmosphere comprising 0.1% to 5% oxygen byvolume. In certain embodiments, methods of the present disclosureinclude the step of incorporating at least one hydrophobic-bound siliconinto the aerogel composition providing a hydrophobic organic content inthe aerogel composition of between about 1 wt % and about 25 wt %. In apreferred embodiment, methods of the present disclosure produce anaerogel composition. In certain embodiments, methods of the presentdisclosure produce an aerogel composition which has the followingproperties: a) a density of 0.60 g/cm³ or less; b) a thermalconductivity of 50 mW/m*K or less; c) a liquid water uptake of 40 wt %or less; d) a heat of combustion between 150 cal/g and 717 cal/g; and e)an onset of thermal decomposition of hydrophobic organic materialtemperature of between 300° C. and 700° C.

In another general aspect, the disclosure can provide a method ofpreparing an aerogel composition, comprising: a) producing a firstaerogel composition comprising at least one hydrophobic-bound silicon;and b) exposing the first aerogel composition to a reduced oxygenatmosphere at a temperature above 300° C. In another general aspect, thedisclosure can provide a method comprising exposing a first aerogelcomposition comprising at least one hydrophobic-bound silicon to areduced oxygen atmosphere at a temperature above 300° C. to obtain asecond aerogel composition. In certain embodiments, methods of thepresent disclosure include exposing the aerogel material or compositionto a reduced oxygen atmosphere at temperatures between 300° C. and 650°C. for a period of time between about 30 seconds and about 200 minutesto obtain a treated aerogel material or composition. In certainembodiments, methods of the present disclosure include the temperatureexposure of the heat treatment of the aerogel material or compositionbeing limited to a temperature below 850° C. In certain embodiments,methods of the present disclosure include aerogel compositions which area silica-based aerogel materials. In certain embodiments, methods of thepresent disclosure include aerogel compositions which are reinforcedaerogel composition. In certain embodiments, methods of the presentdisclosure include reduced oxygen atmospheres comprising 0.1% to 5%oxygen by volume. In certain embodiments, methods of the presentdisclosure include aerogel compositions which have a hydrophobic organiccontent between about 1 wt % and about 25 wt %. In certain embodiments,methods of the present disclosure produce treated aerogel compositionswhich have improved hydrophobicity relative to the aerogel compositionsprior to the treatment method. In certain embodiments, methods of thepresent disclosure produce treated aerogel compositions which have alower liquid water uptake relative to the aerogel compositions prior tothe treatment method. In certain embodiments, methods of the presentdisclosure produce treated aerogel compositions which have a lower heatof combustion relative to the aerogel compositions prior to thetreatment method. In certain embodiments, methods of the presentdisclosure produce treated aerogel compositions which have a higheronset of thermal decomposition temperature relative to the aerogelcompositions prior to the treatment method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a ²⁹Si Solid State NMR spectrum for examples of aerogelcompositions of the present disclosure.

FIG. 2 is a graph depicting the TGA/DSC analysis for examples of aerogelcompositions of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Aerogels are a class of porous materials with open-cells comprising aframework of interconnected structures, with a corresponding network ofpores integrated within the framework, and an interstitial phase withinthe network of pores which is primarily comprised of gases such as air.Aerogels are typically characterized by a low density, a high porosity,a large surface area, and small pore sizes. Aerogels can bedistinguished from other porous materials by their physical andstructural properties.

Within the context of the present disclosure, the term “aerogel” or“aerogel material” refers to a gel comprising a framework ofinterconnected structures, with a corresponding network ofinterconnected pores integrated within the framework, and containinggases such as air as a dispersed interstitial medium; and which ischaracterized by the following physical and structural properties(according to Nitrogen Porosimetry Testing) attributable to aerogels:(a) an average pore diameter ranging from about 2 nm to about 100 nm,(b) a porosity of at least 80% or more, and (c) a surface area of about20 m²/g or more.

Aerogel materials of the present disclosure thus include any aerogels orother open-celled compounds which satisfy the defining elements setforth in previous paragraphs; including compounds which can be otherwisecategorized as xerogels, cryogels, ambigels, microporous materials, andthe like.

Aerogel materials may also be further characterized by additionalphysical properties, including: (d) a pore volume of about 2.0 mL/g ormore, preferably about 3.0 mL/g or more; (e) a density of about 0.50g/cc or less, preferably about 0.25 g/cc or less; and (f) at least 50%of the total pore volume comprising pores having a pore diameter ofbetween 2 and 50 nm; though satisfaction of these additional propertiesis not required for the characterization of a compound as an aerogelmaterial.

Within the context of the present disclosure, the term “innovativeprocessing and extraction techniques” refers to methods of replacing aliquid interstitial phase in a wet-gel material with a gas such as air,in a manner which causes low pore collapse and low shrinkage to theframework structure of the gel Drying techniques, such as ambientpressure evaporation, often introduce strong capillary pressures andother mass transfer limitations at the liquid-vapor interface of theinterstitial phase being evaporated or removed. The strong capillaryforces generated by liquid evaporation or removal can cause significantpore shrinkage and framework collapse within the gel material. The useof innovative processing and extraction techniques during the extractionof a liquid interstitial phase reduces the negative effects of capillaryforces on the pores and the framework of a gel during liquid phaseextraction.

In certain embodiments, an innovative processing and extractiontechnique uses near critical or super critical fluids, or near criticalor super critical conditions, to extract the liquid interstitial phasefrom a wet-gel material. This can be accomplished by removing the liquidinterstitial phase from the gel near or above the critical point of theliquid or mixture of liquids. Co-solvents and solvent exchanges can beused to optimize the near critical or super critical fluid extractionprocess.

In certain embodiments, an innovative processing and extractiontechnique includes the modification of the gel framework to reduce theirreversible effects of capillary pressures and other mass transferlimitations at the liquid-vapor interface. This embodiment can includethe treatment of a gel framework with a hydrophobizing agent, or otherfunctionalizing agents, which allow a gel framework to withstand orrecover from any collapsing forces during liquid phase extractionconducted below the critical point of the liquid interstitial phase.This embodiment can also include the incorporation of functional groupsor framework elements which provide a framework modulus which issufficiently high to withstand or recover from collapsing forces duringliquid phase extraction conducted below the critical point of the liquidinterstitial phase.

Within the context of the present disclosure, the terms “framework” or“framework structure” refer to the network of interconnected oligomers,polymers or colloidal particles that form the solid structure of a gelor an aerogel. The polymers or particles that make up the frameworkstructures typically have a diameter of about 100 angstroms. However,framework structures of the present disclosure can also include networksof interconnected oligomers, polymers or colloidal particles of alldiameter sizes that form the solid structure within in a gel or aerogel.Furthermore, the terms “silica-based aerogel” or “silica-basedframework” refer to an aerogel framework in which silica comprises atleast 50% (by weight) of the oligomers, polymers or colloidal particlesthat form the solid framework structure within in the gel or aerogel.

Within the context of the present disclosure, the term “aerogelcomposition” refers to any composite material which includes aerogelmaterial as a component of the composite. Examples of aerogelcompositions include, but are not limited to: fiber-reinforced aerogelcomposites; aerogel composites which include additive elements such asopacifiers; aerogel-foam composites; aerogel-polymer composites; andcomposite materials which incorporate aerogel particulates, particles,granules, beads, or powders into a solid or semi-solid material, such asbinders, resins, cements, foams, polymers, or similar solid materials.

Within the context of the present invention, the term “monolithic”refers to aerogel materials in which a majority (by weight) of theaerogel included in the aerogel material or composition is in the formof a unitary interconnected aerogel nanostructure. Monolithic aerogelmaterials include aerogel materials which are initially formed to have aunitary interconnected gel or aerogel nanostructure, but which aresubsequently cracked, fractured or segmented into non-unitary aerogelnanostructures. Monolithic aerogel materials are differentiated fromparticulate aerogel materials. The term “particulate aerogel material”refers to aerogel materials in which a majority (by weight) of theaerogel included in the aerogel material is in the form of particulates,particles, granules, beads, or powders, which can be combined orcompressed together but which lack an interconnected aerogelnanostructure between individual particles.

Within the context of the present disclosure, the term “reinforcedaerogel composition” refers to aerogel compositions which comprise areinforcing phase within the aerogel material which is not part of theaerogel framework. The reinforcing phase can be any material whichprovides increased flexibility, resilience, conformability or structuralstability to the aerogel material. Examples of well-known reinforcingmaterials include, but are not limited to: open-cell foam reinforcementmaterials, closed-cell foam reinforcement materials, open-cellmembranes, honeycomb reinforcement materials, polymeric reinforcementmaterials, and fiber reinforcement materials such as discrete fibers,woven materials, non-woven materials, battings, webs, mats, and felts.Additionally, fiber based reinforcements may be combined with one ormore of the other reinforcing materials, and can be orientedcontinuously throughout or in limited preferred parts of thecomposition.

Within the context of the present disclosure, the term “fiber-reinforcedaerogel composition” refers to a reinforced aerogel composition whichcomprises a fiber reinforcement material as a reinforcing phase.Examples of fiber reinforcement materials include, but are not limitedto, discrete fibers, woven materials, non-woven materials, battings,webs, mats, felts, or combinations thereof. Fiber reinforcementmaterials can comprise a range of materials, including, but not limitedto: Polyesters, polyolefin terephthalates, poly(ethylene) naphthalate,polycarbonates (examples Rayon. Nylon), cotton, (e.g. lycra manufacturedby DuPont), carbon (e.g. graphite), polyacrylonitriles (PAN), oxidizedPAN, uncarbonized heat treated PANs (such as those manufactured by SGLcarbon), fiberglass based material (like S-glass, 901 glass, 902 glass,475 glass, E-glass,) silica based fibers like quartz, (e.g. Quartzelmanufactured by Saint-Gobain), Q-felt (manufactured by Johns Manville),Saffil (manufactured by Saffil), Durablanket (manufactured by Unifrax)and other silica fibers, Duraback (manufactured by Carborundum),Polyaramid fibers like Kevlar, Nomex, Sontera (all manufactured byDuPont), Conex (manufactured by Taijin), polyolefins like Tyvek(manufactured by DuPont), Dyneema (manufactured by DSM), Spectra(manufactured by Honeywell), other polypropylene fibers like Typar,Xavan (both manufactured by DuPont), fluoropolymers like PTFE with tradenames as Teflon (manufactured by DuPont), Goretex (manufactured by W.L.GORE), Silicon carbide fibers like Nicalon (manufactured by COICeramics), ceramic fibers like Nextel (manufactured by 3M), Acrylicpolymers, fibers of wool, silk, hemp, leather, suede, PBO-Zylon fibers(manufactured by Tyobo), Liquid crystal material like Vectan(manufactured by Hoechst), Cambrelle fiber (manufactured by DuPont),Polyiurethanes, polyarnaides, Wood fibers, Boron, Aluminum, Iron,Stainless Steel fibers and other thermoplastics like PEEK, PES, PET, PEK, PPS

Within the context of the present disclosure, the terms “aerogelblanket” or “aerogel blanket composition” refer to aerogel compositionsreinforced with a continuous sheet of reinforcement material. Aerogelblanket compositions can be differentiated from other reinforced aerogelcomposition which are reinforced with a non-continuous fiber or foamnetwork, such as separated agglomerates or clumps of fiber materials.Aerogel blanket compositions are particularly useful for applicationsrequiring flexibility, since they are highly conformable and can be usedlike a blanket to cover surfaces of simple or complex geometry, whilealso retaining the excellent thermal insulation properties of aerogels.Aerogel blanket compositions and similar fiber-reinforced aerogelcompositions are described in Published US patent application2002/0094426 (paragraphs 12-16, 25-27, 38-58, 60-88), which is herebyincorporated by reference according to the individually cited sectionsand paragraphs.

Within the context of the present disclosure, the term “wet gel” refersto a gel in which the mobile interstitial phase within the network ofinterconnected pores is primarily comprised of a liquid phase such as aconventional solvent, liquefied gases such as liquid carbon dioxide, ora combination thereof. Aerogels typically require the initial productionof a wet gel, followed by innovative processing and extraction toreplace the mobile interstitial liquid phase in the gel with air.Examples of wet gels include, but are not limited to: alcogels,hydrogels, ketogels, carbonogels, and any other wet gels known to thosein the art.

Within the context of the present disclosure, the terms “additive” or“additive element” refer to materials which can be added to an aerogelcomposition before, during, or after the production of the aerogel.Additives can be added to alter or improve desirable properties in anaerogel, or to counteract undesirable properties in an aerogel.Additives are typically added to an aerogel material either prior orduring gelation. Examples of additives include, but are not limited to:microfibers, fillers, reinforcing agents, stabilizers, thickeners,elastic compounds, opacifiers, coloring or pigmentation compounds,radiation absorbing compounds, radiation reflecting compounds, corrosioninhibitors, thermally conductive components, phase change materials, pHadjustors, redox adjustors, HCN mitigators, off-gas mitigators,electrically conductive compounds, electrically dielectric compounds,magnetic compounds, radar blocking components, hardeners, anti-shrinkingagents, and other aerogel additives known to those in the art. Otherexamples of additives include smoke suppressants and fire suppressants.Published US Pat. App. 20070272902 A1 (Paragraphs [0008] and[0010]-[0039]) includes teachings of smoke suppressants and firesuppressants, and is hereby incorporated by reference according to theindividually cited paragraphs.

Within the context of the present disclosure, the terms “flexible” and“flexibility” refer to the ability of an aerogel material or compositionto be bent or flexed without macrostructural failure. Preferably,aerogel compositions of the present disclosure are capable of bending atleast 5°, at least 25°, at least 45°, at least 65°, or at least 85°without macroscopic failure; and/or have a bending radius of less than 4feet, less than 2 feet, less than 1 foot, less than 6 inches, less than3 inches, less than 2 inches, less than 1 inch, or less than ½ inchwithout macroscopic failure. Likewise, the terms “highly flexible” or“high flexibility” refer to aerogel materials or compositions capable ofbending to at least 900 and/or have a bending radius of less than ½ inchwithout macroscopic failure. Furthermore, the terms “classifiedflexible” and “classified as flexible” refer to aerogel materials orcompositions which can be classified as flexible according to ASTMclassification standard C1101 (ASTM International, West Conshohocken,Pa.).

Aerogel materials or compositions of the present disclosure can beflexible, highly flexible, and/or classified flexible. Aerogel materialsor compositions of the present disclosure can also be drapable. Withinthe context of the present disclosure, the terms “drapable” and“drapability” refer to the ability of an aerogel material or compositionto be bent or flexed to 90° or more with a radius of curvature of about4 inches or less, without macroscopic failure. An aerogel material orcomposition of the present disclosure is preferably flexible such thatthe composition is non-rigid and may be applied and conformed tothree-dimensional surfaces or objects, or pre-formed into a variety ofshapes and configurations to simplify installation or application.

Within the context of the present disclosure, the terms “resilient” and“resilience” refer to the ability of an aerogel material or compositionto at least partially return to an original form or dimension followingdeformation through compression, flexing, or bending. Resilience may becomplete or partial, and it may be expressed in terms of percentagereturn. An aerogel material or composition of the present disclosurepreferably has a resilience of more than 25%, more than 50%, more than60%, more than 70%, more than 75%, more than 80%, more than 85%, morethan 90%, or more than 95% return to an original form or dimensionfollowing a deformation. Likewise, the terms “classified resilient” and“classified as resilient” refer to aerogel materials or compositions ofthe present disclosure which can be classified as resilient flexibleaccording to ASTM classification standard C1101 (ASTM International,West Conshohocken, Pa.).

Within the context of the present disclosure, the term “self-supporting”refers to the ability of an aerogel material or composition to beflexible and/or resilient based primarily on the physical properties ofthe aerogel and any reinforcing phase in the aerogel composition.Self-supporting aerogel materials or compositions of the presentdisclosure can be differentiated from other aerogel materials, such ascoatings, which rely on an underlying substrate to provide flexibilityand/or resilience to the material.

Within the context of the present disclosure, the term “shrinkage”refers to the ratio of: 1) the difference between the measured finaldensity of the dried aerogel material or composition and the targetdensity calculated from solid content in the sol-gel precursor solution,relative to 2) the target density calculated from solid content in thesol-gel precursor solution. Shrinkage can be calculated by the followingequation: Shrinkage=[Final Density (g/cm³)−Target Density(g/cm³)]/[Target Density (g/cm³)]. Preferably, shrinkage of an aerogelmaterial of the present disclosure is preferably 50% or less, 25% orless, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% orless, 2% or less, 1% or less, 0.1% or less, about 0.01% or less, or in arange between any two of these values.

Within the context of the present disclosure, the terms “thermalconductivity” and “TC” refer to a measurement of the ability of amaterial or composition to transfer heat between two surfaces on eitherside of the material or composition, with a temperature differencebetween the two surfaces. Thermal conductivity is specifically measuredas the heat energy transferred per unit time and per unit surface area,divided by the temperature difference. It is typically recorded in SIunits as mW/m*K (milliwatts per meter*Kelvin). The thermal conductivityof a material may be determined by methods known in the art, including,but not limited to: Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter Apparatus (ASTM C518, ASTMInternational, West Conshohocken, Pa.); a Test Method for Steady-StateHeat Flux Measurements and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate Apparatus (ASTM C177, ASTM International, WestConshohocken, Pa.); a Test Method for Steady-State Heat TransferProperties of Pipe Insulation (ASTM C335, ASTM International, WestConshohocken, Pa.); a Thin Heater Thermal Conductivity Test (ASTM C1114,ASTM International, West Conshohocken, Pa.); Determination of thermalresistance by means of guarded hot plate and heat flow meter methods (EN12667, British Standards Institution, United Kingdom); or Determinationof steady-state thermal resistance and related properties—Guarded hotplate apparatus (ISO 8203, International Organization forStandardization, Switzerland). Within the context of the presentdisclosure, thermal conductivity measurements are acquired according toASTM C177 standards, at a temperature of about 37.5° C. at atmosphericpressure, and a compression of about 2 psi, unless otherwise stated.Preferably, aerogel materials or compositions of the present disclosurehave a thermal conductivity of about 50 mW/mK or less, about 40 mW/mK orless, about 30 mW/mK or less, about 25 mW/mK or less, about 20 mW/mK orless, about 18 mW/mK or less, about 16 mW/mK or less, about 14 mW/mK orless, about 12 mW/mK or less, about 10 mW/mK or less, about 5 mW/mK orless, or in a range between any two of these values.

Within the context of the present disclosure, the term “density” refersto a measurement of the mass per unit volume of an aerogel material orcomposition. The term “density” generally refers to the true density ofan aerogel material, as well as the bulk density of an aerogelcomposition. Density is typically recorded as kg/m³ or g/cc. The densityof an aerogel material or composition may be determined by methods knownin the art, including, but not limited to: Standard Test Method forDimensions and Density of Preformed Block and Board-Type ThermalInsulation (ASTM C303, ASTM International, West Conshohocken, Pa.);Standard Test Methods for Thickness and Density of Blanket or BattThermal Insulations (ASTM C167, ASTM International, West Conshohocken,Pa.); or Determination of the apparent density of preformed pipeinsulation (ISO 18098, International Organization for Standardization,Switzerland). Within the context of the present disclosure, densitymeasurements are acquired according to ASTM C167 standards, unlessotherwise stated. Preferably, aerogel materials or compositions of thepresent disclosure have a density of about 0.60 g/cc or less, about 0.50g/cc or less, about 0.40 g/cc or less, about 0.30 g/cc or less, about0.25 g/cc or less, about 0.20 g/cc or less, about 0.18 g/cc or less,about 0.16 g/cc or less, about 0.14 g/cc or less, about 0.12 g/cc orless, about 0.10 g/cc or less, about 0.05 g/cc or less, about 0.01 g/ccor less, or in a range between any two of these values.

Within the context of the present disclosure, the term “hydrophobicity”refers to a measurement of the ability of an aerogel material orcomposition to repel water.

Hydrophobicity of an aerogel material or composition can be expressed interms of the liquid water uptake. Within the context of the presentdisclosure, the term “liquid water uptake” refers to a measurement ofthe potential of an aerogel material or composition to absorb orotherwise retain liquid water. Liquid water uptake can be expressed as apercent (by weight or by volume) of water which is absorbed or otherwiseretained by an aerogel material or composition when exposed to liquidwater under certain measurement conditions. The liquid water uptake ofan aerogel material or composition may be determined by methods known inthe art, including, but not limited to: Standard Test Method forDetermining the Water Retention (Repellency) Characteristics of FibrousGlass Insulation (ASTM C1511, ASTM International, West Conshohocken,Pa.); Standard Test Method for Water Absorption by Immersion of ThermalInsulation Materials (ASTM C1763, ASTM International, West Conshohocken,Pa.); Thermal insulating products for building applications:Determination of short term water absorption by partial immersion (EN1609, British Standards Institution, United Kingdom). Within the contextof the present disclosure, measurements of liquid water uptake areacquired according to ASTM C1511 standards, under ambient pressure andtemperature, unless otherwise stated. Preferably, aerogel materials orcompositions of the present disclosure can have a liquid water uptake ofaccording to ASTM C1511 of about 100 wt % or less, about 80 wt % orless, about 60 wt % or less, about 50 wt % or less, about 40 wt % orless, about 30 wt % or less, about 20 wt % or less, about 15 wt % orless, about 10 wt % or less, about 8 wt % or less, about 3 wt % or less,about 2 wt % or less, about 1 wt % or less, about 0.1 wt % or less, orin a range between any two of these values. Aerogel materials orcompositions of the present disclosure can have a liquid water uptake ofaccording to ASTM C1763 of about 100 vol wt % or less, about 80 wt % orless, about 60 wt % or less, about 50 wt % or less, about 40 wt % orless, about 30 wt % or less, about 20 wt % or less, about 15 wt % orless, about 10 wt % or less, about 8 wt % or less, about 3 wt % or less,about 2 wt % or less, about 1 wt % or less, about 0.1 wt % or less, orin a range between any two of these values. An aerogel material orcomposition which has improved liquid water uptake relative to anotheraerogel material or composition will have a lower percentage of liquidwater uptake/retention relative to the reference aerogel materials orcompositions.

Hydrophobicity of an aerogel material or composition can be expressed interms of the water vapor uptake. Within the context of the presentdisclosure, the term “water vapor uptake” refers to a measurement of thepotential of an aerogel material or composition to absorb water vapor.Water vapor uptake can be expressed as a percent (by weight) of waterwhich is absorbed or otherwise retained by an aerogel material orcomposition when exposed to water vapor under certain measurementconditions. The water vapor uptake of an aerogel material or compositionmay be determined by methods known in the art, including, but notlimited to: Standard Test Method for Determining the Water VaporSorption of Unfaced Mineral Fiber Insulation (ASTM C1104, ASTMInternational, West Conshohocken, Pa.). Within the context of thepresent disclosure, measurements of water vapor uptake are acquiredaccording to ASTM C1104 standards, under ambient pressure andtemperature, unless otherwise stated. Preferably, aerogel materials orcompositions of the present disclosure can have a water vapor uptake ofabout 50 wt % or less, about 40 wt % or less, about 30 wt % or less,about 20 wt % or less, about 15 wt % or less, about 10 wt % or less,about 8 wt % or less, about 3 wt % or less, about 2 wt % or less, about1 wt % or less, about 0.1 wt % or less, or in a range between any two ofthese values. An aerogel material or composition which has improvedwater vapor uptake relative to another aerogel material or compositionwill have a lower percentage of water vapor uptake/retention relative tothe reference aerogel materials or compositions.

Hydrophobicity of an aerogel material or composition can be expressed bymeasuring the equilibrium contact angle of a water droplet at theinterface with the surface of the material. Aerogel materials orcompositions of the present disclosure can have a water contact angle ofabout 90° or more, about 120° or more, about 130° or more, about 140° ormore, about 150° or more, about 160° or more, about 170° or more, about175° or more, or in a range between any two of these values.

Within the context of the present disclosure, the terms “heat ofcombustion” and “HOC” refer to a measurement of the amount of heatenergy released in the combustion of an aerogel material or composition.Heat of combustion is typically recorded in calories of heat energyreleased per gram of aerogel material or composition (cal/g), or asmegajoules of heat energy released per kilogram of aerogel material orcomposition (MJ/kg). The heat of combustion of a material or compositionmay be determined by methods known in the art, including, but notlimited to: Reaction to fire tests for products—Determination of thegross heat of combustion (calorific value) (ISO 1716, InternationalOrganization for Standardization, Switzerland). Within the context ofthe present disclosure, heat of combustion measurements are acquiredaccording to conditions comparable to ISO 1716 standards, unlessotherwise stated. Preferably, aerogel compositions of the presentdisclosure can have a heat of combustion of about 750 cal/g or less,about 717 cal/g or less, about 700 cal/g or less, about 650 cal/g orless, about 600 cal/g or less, about 575 cal/g or less, about 550 cal/gor less, about 500 cal/g or less, about 450 cal/g or less, about 400cal/g or less, about 350 cal/g or less, about 300 cal/g or less, about250 cal/g or less, about 200 cal/g or less, about 150 cal/g or less,about 100 cal/g or less, about 50 cal/g or less, about 25 cal/g or less,about 10 cal/g or less, or in a range between any two of these values.An aerogel composition which has an improved heat of combustion relativeto another aerogel composition will have a lower heat of combustionvalue, relative to the reference aerogel compositions.

Within the context of the present disclosure, the terms “onset ofthermal decomposition of hydrophobic organic material”, “onset ofthermal decomposition” and “Td” refer to a measurement of the lowesttemperature of environmental heat at which rapid exothermic reactionsfrom the decomposition of hydrophobic organic material appear within amaterial or composition. The onset of thermal decomposition of amaterial or composition may be measured using thermo-gravimetricanalysis (TGA). The TGA curve of a material depicts the weight loss (%mass) of a material as it is exposed to an increase in surroundingtemperature. The onset of thermal decomposition of a material can becorrelated with the intersection point of the following tangent lines ofthe TGA curve: a line tangent to the base line of the TGA curve, and aline tangent to the TGA curve at the point of maximum slope during therapid decomposition event related to the decomposition of hydrophobicorganic material. Within the context of the present disclosure,measurements of the onset of thermal decomposition of hydrophobicorganic material are acquired using TGA analysis as provided in thisparagraph, unless otherwise stated.

The onset of thermal decomposition of a material may also be measuredusing differential scanning calorimetry (DSC) analysis. The DSC curve ofa material depicts the heat energy (mW/mg) released by a material as itis exposed to a gradual increase in surrounding temperature. The onsetof thermal decomposition temperature of a material can be correlatedwith the point in the DSC curve where the A mW/mg (change in the heatenergy output) maximally increases, thus indicating exothermic heatproduction from the aerogel material. Within the context of the presentdisclosure, measurements of onset of thermal decomposition using DSC areacquired using a temperature ramp rate of 20° C./min or less, unlessotherwise stated.

Preferably, aerogel materials or compositions of the present disclosurehave an onset of thermal decomposition of about 100° C. or more, about150° C. or more, about 200° C. or more, about 250° C. or more, about300° C. or more, about 350° C. or more, about 400° C. or more, about450° C. or more, about 500° C. or more, about 550° C. or more, about600° C. or more, about 650° C. or more, about 700° C. or more, about750° C. or more, about 800° C. or more, or in a range between any two ofthese values. An aerogel material or composition which has an improvedonset of thermal decomposition relative to another aerogel material orcomposition will have a higher onset of thermal decompositiontemperature relative to the reference aerogel material or composition.

Within the context of the present disclosure, the term “self-heatingtemperature” refers to a measurement of the lowest temperature ofenvironmental heat at which exothermic reactions appear under specificmeasurement conditions within an insulation system, such as aninsulation system comprising an aerogel material or composition. Withinthe context of the present disclosure, measurements of the self-heatingtemperature of an insulation system are measured according to thefollowing procedure, unless otherwise specified: a) providing aninsulation system which is geometrically cubic with a dimension of 20 mmon each side; b) placing a thermocouple measuring device at the centerof the insulation system; and c) exposing the insulation system to aseries of increasing temperatures until an self-heating exothermic eventoccurs, which is indicated by the temperature of the thermocouplemeasuring device exceeding the external exposure temperature of thesample by an amount significant enough to indicate a self-heatingexothermic event within the insulation system. Preferably, aerogelmaterials or compositions of the present disclosure have a self-heatingtemperature of about 100° C. or more, about 150° C. or more, about 200°C. or more, about 250° C. or more, about 300° C. or more, about 350° C.or more, about 400° C. or more, about 450° C. or more, about 500° C. ormore, about 550° C. or more, about 600° C. or more, about 650° C. ormore, about 700° C. or more, about 750° C. or more, about 800° C. ormore, or in a range between any two of these values. An aerogel materialor composition which has an improved self-heating temperature relativeto another aerogel material or composition will have a higherself-heating temperature relative to the reference aerogel material orcomposition.

Aerogels are described as a framework of interconnected structures whichare most commonly comprised of interconnected oligomers, polymers orcolloidal particles. An aerogel framework can be made from a range ofprecursor materials, including: inorganic precursor materials (such asprecursors used in producing silica-based aerogels); organic precursormaterials (such precursors used in producing carbon-based aerogels);hybrid inorganic/organic precursor materials; and combinations thereof.Within the context of the present disclosure, the term “amalgam aerogel”refers to an aerogel produced from a combination of two or moredifferent gel precursors.

Inorganic aerogels are generally formed from metal oxide or metalalkoxide materials. The metal oxide or metal alkoxide materials can bebased on oxides or alkoxides of any metal that can form oxides. Suchmetals include, but are not limited to: silicon, aluminum, titanium,zirconium, hafnium, yttrium, vanadium, cerium, and the like. Inorganicsilica aerogels are traditionally made via the hydrolysis andcondensation of silica-based alkoxides (such as tetraethoxylsilane), orvia gelation of silicic acid or water glass. Other relevant inorganicprecursor materials for silica based aerogel synthesis include, but arenot limited to: metal silicates such as sodium silicate or potassiumsilicate, alkoxysilanes, partially hydrolyzed alkoxysilanes,tetraethoxylsilane (TEOS), partially hydrolyzed TEOS, condensed polymersof TEOS, tetramethoxylsilane (TMOS), partially hydrolyzed TMOS,condensed polymers of TMOS, tetra-n-propoxysilane, partially hydrolyzedand/or condensed polymers of tetra-n-propoxysilane, polyethylsilicates,partially hydrolyzed polyethysilicates, monomeric alkylalkoxy silanes,bis-trialkoxy alkyl or aryl silanes, polyhedral silsesquioxanes, orcombinations thereof.

In certain embodiments of the present disclosure, pre-hydrolyzed TEOS,such as Silbond H-5 (SBH5, Silbond Corp), which is hydrolyzed with awater/silica ratio of about 1.9-2, may be used as commercially availableor may be further hydrolyzed prior to incorporation into the gellingprocess. Partially hydrolyzed TEOS or TMOS, such as polyethysilicate(Silbond 40) or polymethylsilicate may also be used as commerciallyavailable or may be further hydrolyzed prior to incorporation into thegelling process.

Inorganic aerogels can also include gel precursors which comprise atleast one hydrophobic group, such as alkyl metal alkoxides, cycloalkylmetal alkoxides, and aryl metal alkoxides, which can impart or improvecertain properties in the gel such as stability and hydrophobicity.Inorganic silica aerogels can specifically include hydrophobicprecursors such as alkylsilanes or arylsilanes. Hydrophobic gelprecursors can be used as primary precursor materials to form theframework of a gel material. However, hydrophobic gel precursors aremore commonly used as coprecursors in combination with simple metalalkoxides in the formation of amalgam aerogels. Hydrophobic inorganicprecursor materials for silica based aerogel synthesis include, but arenot limited to: trimethyl methoxysilane [TMS], dimethyl dimethoxysilane[DMS], methyl trimethoxysilane [MTMS], trimethyl ethoxysilane, dimethyldiethoxysilane [DMDS], methyl triethoxysilane [MTES], ethyltriethoxysilane [ETES], diethyl diethoxysilane, ethyl triethoxysilane,propyl trimethoxysilane, propyl triethoxysilane, phenyltrimethoxysilane, phenyl triethoxysilane [PhTES], hexamethyldisilazaneand hexaethyldisilazane, and the like.

Aerogels may also be treated to impart or improve hydrophobicity.Hydrophobic treatment can be applied to a sol-gel solution, a wet-gelprior to liquid phase extraction, or to an aerogel subsequent to liquidphase extraction. Hydrophobic treatment is especially common in theproduction of metal oxide aerogels, such as silica aerogels. An exampleof a hydrophobic treatment of a gel is discussed below in greaterdetail, specifically in the context of treating a silica wet-gel.However, the specific examples and illustrations provided herein are notintended to limit the scope of the present disclosure to any specifictype of hydrophobic treatment procedure or aerogel substrate. Thepresent disclosure can include any gel or aerogel known to those in theart, as well as associated methods of hydrophobic treatment of theaerogels, in either wet-gel form or dried aerogel form.

Hydrophobic treatment is carried out by reacting a hydroxy moiety on agel, such as a silanol group (Si—OH) present on a framework of a silicagel, with a functional group of a hydrophobizing agent. The resultingreaction converts the silanol group and the hydrophobizing agent into ahydrophobic group on the framework of the silica gel. The hydrophobizingagent compound can react with hydroxyl groups on the gel according thefollowing reaction: R_(N)MX_(4-N) (hydrophobizing agent)+MOH(silanol)→MOMR_(N) (hydrophobic group)+HX. Hydrophobic treatment cantake place both on the outer macro-surface of a silica gel, as well ason the inner-pore surfaces within the porous network of a gel.

A gel can be immersed in a mixture of a hydrophobizing agent and anoptional hydrophobic-treatment solvent in which the hydrophobizing agentis soluble, and which is also miscible with the gel solvent in thewet-gel. A wide range of hydrophobic-treatment solvents can be used,including solvents such as methanol, ethanol, isopropanol, xylene,toluene, benzene, dimethylformamide, and hexane. Hydrophobizing agentsin liquid or gaseous form may also be directly contacted with the gel toimpart hydrophobicity.

The hydrophobic treatment process can include mixing or agitation tohelp the hydrophobizing agent to permeate the wet-gel. The hydrophobictreatment process can also include varying other conditions such astemperature and pH to further enhance and optimize the treatmentreactions. After the reaction is completed, the wet-gel is washed toremove unreacted compounds and reaction by-products.

Hydrophobizing agents for hydrophobic treatment of an aerogel aregenerally compounds of the formula: R_(N)MX_(4-N); where M is the metal;R is a hydrophobic group such as CH₃, CH₂CH₃, C₆H₆, or similarhydrophobic alkyl, cycloalkyl, or aryl moieties; and X is a halogen,usually Cl. Specific examples of hydrophobizing agents include, but arenot limited to: trimethylchlorosilane [TMCS], triethylchlorosilane[TECS], triphenylchlorosilane [TPCS], dimethylchlorosilane [DMCS],dimethyldichlorosilane [DMDCS], and the like. Hydrophobizing agents canalso be of the formula: Y(R₃M)₂; where M is a metal; Y is bridging groupsuch as NH or O; and R is a hydrophobic group such as CH₃, CH₂CH₃, C₆H₆,or similar hydrophobic alkyl, cycloalkyl, or aryl moieites. Specificexamples of such hydrophobizing agents include, but are not limited to:hexamethyldisilazane [HMDZ] and hexamethyldisiloxane [HMDSO].Hydrophobizing agents can further include compounds of the formula:R_(N)MV_(4-N), wherein V is a reactive or leaving group other than ahalogen. Specific examples of such hydrophobizing agents include, butare not limited to: vinyltriethoxysilane and vinyltrimethoxysilane.

Within the context of the present disclosure, the term“hydrophobic-bound silicon” refers to a silicon atom within theframework of a gel or aerogel which comprises at least one hydrophobicgroup covalently bonded to the silicon atom. Examples ofhydrophobic-bound silicon include, but are not limited to, silicon atomsin silica groups within the gel framework which are formed from gelprecursors comprising at least one hydrophobic group (such as MTES orDMDS). Hydrophobic-bound silicon can also include, but are not limitedto, silicon atoms in the gel framework or on the surface of the gelwhich are treated with a hydrophobizing agent (such as HMDZ) to impartor improve hydrophobicity by incorporating additional hydrophobic groupsinto the composition. Hydrophobic groups of the present disclosureinclude, but are not limited to, methyl groups, ethyl groups, propylgroups, isopropyl groups, butyl groups, isobutyl groups, tertbutylgroups, octyl groups, phenyl groups, or other substituted orunsubstituted hydrophobic organic groups known to those with skill inthe art. Within the context of the present disclosure, the terms“hydrophobic group,” “hydrophobic organic material,” and “hydrophobicorganic content” specifically exclude readily hydrolysable organicsilicon-bound alkoxy groups on the framework of the gel material whichare the product of reactions between organic solvents and silanolgroups.

Within the context of the present disclosure, the terms “aliphatichydrophobic group,” “aliphatic hydrophobic organic material,” and“aliphatic hydrophobic organic content” describe hydrophobic groups onhydrophobic-bound silicon which are limited to aliphatic hydrocarbons,including, but not limited to hydrocarbon moieties containing 1-40carbon atoms which can be saturated or unsaturated (but not aromatic),which can include straight-chain, branched, cyclic moieties (includingfused, bridging, and spiro-fused polycyclic), or combinations thereof,such as alkyl, alkenyl, alkynyl, (cycloalkyl)alkyl, (cycloalkenyl)alkyl,or (cycloalkyl)alkenyl moieties, and hetero-aliphatic moieties (whereinone or more carbon atoms are independently replaced by one or more atomsselected from the group consisting of oxygen, sulfur, nitrogen, orphosphorus). In certain embodiments of the present disclosure, at least50% of the hydrophobic organic material in the aerogel compositioncomprises aliphatic hydrophobic groups.

The amount of hydrophobic-bound silicon contained in an aerogel can beanalyzed using NMR spectroscopy, such as CP/MAS ²⁹Si Solid State NMR. AnNMR analysis of an aerogel allows for the characterization and relativequantification of: M-type hydrophobic-bound silicon (monofunctionalsilica, such as TMS derivatives); D-type hydrophobic-bound silicon(bifunctional silica, such as DMDS derivatives); T-typehydrophobic-bound silicon (trifunctional silica, such as MTESderivatives); and Q-type silicon (quadfunctional silica, such as TEOSderivatives). NMR analysis can also be used to analyze the bondingchemistry of hydrophobic-bound silicon contained in an aerogel byallowing for categorization of specific types of hydrophobic-boundsilicon into sub-types (such as the categorization of T-typehydrophobic-bound silicon into T¹ species, T² species, and T³ species).Specific details related to the NMR analysis of silica materials can befound in the article “Applications of Solid-State NMR to the Study ofOrganic/Inorganic Multicomponent Materials” by Geppi et al.,specifically pages 7-9 (Appl. Spec. Rev. (2008), 44-1: 1-89), which ishereby incorporated by reference according to the specifically citedpages.

The characterization of hydrophobic-bound silicon in a CP/MAS ²⁹Si NMRanalysis can be based on the following chemical shift peaks: M¹ (30 to10 ppm); D¹ (10 to −10 ppm), D² (−10 to −20 ppm); T¹ (−30 to −40 ppm),T² (−40 to −50 ppm), T³ (−50 to −70 ppm); Q² (−70 to −85 ppm), Q³ (−85to −95 ppm), Q⁴ (−95 to −110 ppm). These chemical shift peaks areapproximate and exemplary, and are not intended to be limiting ordefinitive. The precise chemical shift peaks attributable to the varioussilicon species within a material can depend on the specific chemicalcomponents of the material, and can generally be deciphered throughroutine experimentation and analysis by those in the art.

The aerogel materials of the present disclosure can have a ratio ofT¹⁻²:T³ of between about 0.01 and about 0.5, between about 0.01 andabout 0.3, or between about 0.1 and about 0.3. A ratio of T¹⁻²:T³represents a ratio of a combination of T¹ and T² species relative to T³species. The amount of T¹, T² and T³ can quantified by the integral ofthe individual chemical shift peaks respectively associated with T¹species, T² species or T³ species in a ²⁹Si NMR analysis, as previouslydefined. The aerogel materials of the present disclosure can have aratio of Q²⁻³:Q⁴ of between about 0.1 and 2.5, between about 0.1 and2.0, between about 0.1 and 1.5, between about 0.1 and 1.0, or betweenabout 0.5 and 1.0. A ratio of Q²⁻³:Q⁴ represents a ratio of acombination of Q² and Q³ species relative to Q⁴ species. The amount ofQ², Q³ and Q⁴ can quantified by the integral of the individual chemicalshift peak respectively associated with Q² species, Q³ species or Q⁴species in a ²⁹Si NMR analysis, as previously defined.

Within the context of the present disclosure, the term “hydrophobicorganic content” refers to the amount of hydrophobic organic materialbound to the framework in an aerogel material or composition. Thehydrophobic organic content of an aerogel material or composition can beexpressed as a weight percentage of the amount of hydrophobic organicmaterial on the aerogel framework relative to the total amount ofmaterial in the aerogel material or composition. Hydrophobic organiccontent can be calculated by those with ordinary skill in the art basedon the nature and relative concentrations of materials used in producingthe aerogel material or composition. Hydrophobic organic content canalso be measured using thermo-gravimetric analysis (TGA) in an inertatmosphere. Specifically, the percentage of hydrophobic organic materialin an aerogel can be correlated with the percentage of weight loss in ahydrophobic aerogel material or composition when subjected to combustiveheat temperatures during a TGA analysis, with adjustments being made forthe loss of moisture, loss of residual solvent, and the loss of readilyhydrolysable alkoxy groups during the TGA analysis.

Aerogel materials or compositions of the present disclosure can have ahydrophobic organic content of 50 wt % or less, 40 wt % or less, 30 wt %or less, 25 wt % or less, 20 wt % or less, 15 wt % or less, 10 wt % orless, 8 wt % or less, 6 wt % or less, 5 wt % or less, 4 wt % or less, 3wt % or less, 2 wt % or less, 1 wt % or less, or in a range between anytwo of these values.

The term “fuel content” refers to the total amount of combustiblematerial in an aerogel material or composition, which can be correlatedwith the total percentage of weight loss in an aerogel material orcomposition when subjected to combustive heat temperatures during a TGAor TG-DSC analysis, with adjustments being made for the loss ofmoisture. The fuel content of an aerogel material or composition caninclude hydrophobic organic content, as well as other combustiblematerials such as residual alcoholic solvents, filler materials,reinforcing materials, and readily hydrolysable alkoxy groups.

Organic aerogels are generally formed from carbon-based polymericprecursors. Such polymeric materials include, but are not limited to:resorcinol formaldehydes (RF), polyimide, polyacrylate, polymethylmethacrylate, acrylate oligomers, polyoxyalkylene, polyurethane,polyphenol, polybutadiane, trialkoxysilyl-terminatedpolydimethylsiloxane, polystyrene, polyacrylonitrile, polyfurfural,melamine-formaldehyde, cresol formaldehyde, phenol-furfural, polyether,polyol, polyisocyanate, polyhydroxybenze, polyvinyl alcohol dialdehyde,polycyanurates, polyacrylamides, various epoxies, agar, agarose,chitosan, and combinations thereof. As one example, organic RF aerogelsare typically made from the sol-gel polymerization of resorcinol ormelamine with formaldehyde under alkaline conditions.

Organic/inorganic hybrid aerogels are mainly comprised of ormosil(organically modified silica) aerogels. These ormosil materials includeorganic components which are covalently bonded to a silica network.Ormosils are typically formed through the hydrolysis and condensation oforganically modified silanes, R—Si(OX)₃, with traditional alkoxideprecursors, Y(OX)₄. In these formulas: X may represent, for example,CH₃, C₂H₅, C₃H₇, C₄H₉; Y may represent, for example, Si, Ti, Zr, or Al;and R may be any organic fragment such as methyl, ethyl, propyl, butyl,isopropyl, methacrylate, acrylate, vinyl, epoxide, and the like. Theorganic components in ormosil aerogel may also be dispersed throughoutor chemically bonded to the silica network.

Within the context of the present disclosure, the term “ormosil”encompasses the foregoing materials as well as other organicallymodified ceramics, sometimes referred to as “ormocers.” Ormosils areoften used as coatings where an ormosil film is cast over a substratematerial through, for example, the sol-gel process. Examples of otherorganic-inorganic hybrid aerogels of the disclosure include, but are notlimited to, silica-polyether, silica-PMMA, silica-chitosan, carbides,nitrides, and other combinations of the aforementioned organic andinorganic aerogel forming compounds. Published US Pat. App. 20050192367(Paragraphs [0022]-[0038] and [0044]-[0058]) includes teachings of suchhybrid organic-inorganic materials, and is hereby incorporated byreference according to the individually cited sections and paragraphs.

Aerogels of the present disclosure are preferably inorganic silicaaerogels formed primarily from alcohol solutions of hydrolyzed silicateesters formed from silicon alkoxides. However, the disclosure as a wholemay be practiced with any other aerogel compositions known to those inthe art, and is not limited to any one precursor material or amalgammixture of precursor materials.

Production of an aerogel generally includes the following steps: i)formation of a sol-gel solution; ii) formation of a gel from the sol-gelsolution; and iii) extracting the solvent from the gel materials throughinnovative processing and extraction, to obtain a dried aerogelmaterial. This process is discussed below in greater detail,specifically in the context of forming inorganic aerogels such as silicaaerogels. However, the specific examples and illustrations providedherein are not intended to limit the present disclosure to any specifictype of aerogel and/or method of preparation. The present disclosure caninclude any aerogel formed by any associated method of preparation knownto those in the art.

The first step in forming an inorganic aerogel is generally theformation of a sol-gel solution through hydrolysis and condensation ofmetal alkoxide precursors in an alcohol-based solvent. Major variablesin the formation of inorganic aerogels include the type of alkoxideprecursors included in the sol-gel solution, the nature of the solvent,the processing temperature and pH of the sol-gel solution (which may bealtered by addition of an acid or a base), and precursor/solvent/waterratio within the sol-gel solution. Control of these variables in forminga sol-gel solution can permit control of the growth and aggregation ofthe gel framework during the subsequent transition of the gel materialfrom the “sol” state to the “gel” state. While properties of theresulting aerogels are affected by the pH of the precursor solution andthe molar ratio of the reactants, any pH and any molar ratios thatpermit the formation of gels may be used in the present disclosure.

A sol-gel solution is formed by combining at least one gelling precursorwith a solvent. Suitable solvents for use in forming a sol-gel solutioninclude lower alcohols with 1 to 6 carbon atoms, preferably 2 to 4,although other solvents can be used as known to those with skill in theart. Examples of useful solvents include, but are not limited to:methanol, ethanol, isopropanol, ethyl acetate, ethyl acetoacetate,acetone, dichloromethane, tetrahydrofuran, and the like. Multiplesolvents can also be combined to achieve a desired level of dispersionor to optimize properties of the gel material. Selection of optimalsolvents for the sol-gel and gel formation steps thus depends on thespecific precursors, fillers and additives being incorporated into thesol-gel solution; as well as the target processing conditions forgelling and liquid phase extraction, and the desired properties of thefinal aerogel materials.

Water can also be present in the precursor-solvent solution. The wateracts to hydrolyze the metal alkoxide precursors into metal hydroxideprecursors. The hydrolysis reaction can be (using TEOS in ethanolsolvent as an example): Si(OC₂H₅)₄+4H₂O→Si(OH)₄+4(C₂H₅OH). The resultinghydrolyzed metal hydroxide precursors remain suspended in the solventsolution in a “sol” state, either as individual molecules or as smallpolymerized (or oligomerized) colloidal clusters of molecules. Forexample, polymerization/condensation of the Si(OH)₄ precursors can occuras follows: 2 Si(OH)₄═(OH)₃Si—O—Si(OH)₃+H₂O. This polymerization cancontinue until colloidal clusters of polymerized (or oligomerized) SiO₂(silica) molecules are formed.

Acids and bases can be incorporated into the sol-gel solution to controlthe pH of the solution, and to catalyze the hydrolysis and condensationreactions of the precursor materials. While any acid may be used tocatalyze precursor reactions and to obtain a lower pH solution,preferable acids include: HCl, H₂SO₄, H₃PO₄, oxalic acid and aceticacid. Any base may likewise be used to catalyze precursor reactions andto obtain a higher pH solution, with a preferable base comprising NH₄OH.

The sol-gel solution can include additional co-gelling precursors, aswell as filler materials and other additives. Filler materials and otheradditives may be dispensed in the sol-gel solution at any point beforeor during the formation of a gel. Filler materials and other additivesmay also be incorporated into the gel material after gelation throughvarious techniques known to those in the art. Preferably, the sol-gelsolution comprising the gelling precursors, solvents, catalysts, water,filler materials and other additives is a homogenous solution which iscapable of effective gel formation under suitable conditions.

Once a sol-gel solution has been formed and optimized, the gel-formingcomponents in the sol-gel can be transitioned into a gel material. Theprocess of transitioning gel-forming components into a gel materialcomprises an initial gel formation step wherein the gel solidifies up tothe gel point of the gel material. The gel point of a gel material maybe viewed as the point where the gelling solution exhibits resistance toflow and/or forms a substantially continuous polymeric frameworkthroughout its volume. A range of gel-forming techniques are known tothose in the art. Examples include, but are not limited to: maintainingthe mixture in a quiescent state for a sufficient period of time;adjusting the pH of the solution; adjusting the temperature of thesolution; directing a form of energy onto the mixture (ultraviolet,visible, infrared, microwave, ultrasound, particle radiation,electromagnetic); or a combination thereof.

The process of transitioning gel-forming components into a gel materialcan also include an aging step (also referred to as curing) prior toliquid phase extraction. Aging a gel material after it reaches its gelpoint can further strengthen the gel framework by increasing the numberof cross-linkages within the network. The duration of gel aging can beadjusted to control various properties within the resulting aerogelmaterial. This aging procedure can be useful in preventing potentialvolume loss and shrinkage during liquid phase extraction. Aging caninvolve: maintaining the gel (prior to extraction) at a quiescent statefor an extended period; maintaining the gel at elevated temperatures;adding cross-linkage promoting compounds; or any combination thereof.The preferred temperatures for aging are usually between about 10° C.and about 100° C. The aging of a gel material typically continues up tothe liquid phase extraction of the wet-gel material.

The time period for transitioning gel-forming materials into a gelmaterial includes both the duration of the initial gel formation (frominitiation of gelation up to the gel point), as well as the duration ofany subsequent curing and aging of the gel material prior to liquidphase extraction (from the gel point up to the initiation of liquidphase extraction). The total time period for transitioning gel-formingmaterials into a gel material is typically between about 1 minute andseveral days, preferably about 30 hours or less, about 24 hours or less,about 15 hours or less, about 10 hours or less, about 6 hours or less,about 4 hours or less, about 2 hours or less, about 1 hour or less,about 30 minutes or less, or about 15 minutes or less.

The resulting gel material may be washed in a suitable secondary solventto replace the primary reaction solvent present in the wet-gel. Suchsecondary solvents may be linear monohydric alcohols with 1 or morealiphatic carbon atoms, dihydric alcohols with 2 or more carbon atoms,branched alcohols, cyclic alcohols, alicyclic alcohols, aromaticalcohols, polyhydric alcohols, ethers, ketones, cyclic ethers or theirderivative.

Once a gel material has been formed and processed, the liquid phase ofthe gel can then be at least partially extracted from the wet-gel usingextraction methods, including innovative processing and extractiontechniques, to form an aerogel material. Liquid phase extraction, amongother factors, plays an important role in engineering thecharacteristics of aerogels, such as porosity and density, as well asrelated properties such as thermal conductivity. Generally, aerogels areobtained when a liquid phase is extracted from a gel in a manner thatcauses low shrinkage to the porous network and framework of the wet gel.

Aerogels are commonly formed by removing the liquid mobile phase fromthe gel material at a temperature and pressure near or above thecritical point of the liquid mobile phase. Once the critical point isreached (near critical) or surpassed (supercritical) (i.e pressure andtemperature of the system is at or higher than the critical pressure andcritical temperature respectively) a new supercritical phase appears inthe fluid that is distinct from the liquid or vapor phase. The solventcan then be removed without introducing a liquid-vapor interface,capillary pressure, or any associated mass transfer limitationstypically associated with liquid-vapor boundaries. Additionally, thesupercritical phase is more miscible with organic solvents in general,thus having the capacity for better extraction. Co-solvents and solventexchanges are also commonly used to optimize the supercritical fluiddrying process.

If evaporation or extraction occurs below the supercritical point,capillary forces generated by liquid evaporation can cause shrinkage andpore collapse within the gel material. Maintaining the mobile phase nearor above the critical pressure and temperature during the solventextraction process reduces the negative effects of such capillaryforces. In certain embodiments of the present disclosure, the use ofnear-critical conditions just below the critical point of the solventsystem may allow production of aerogel materials or compositions withsufficiently low shrinkage, thus producing a commercially viableend-product.

Several additional aerogel extraction techniques are known in the art,including a range of different approaches in the use of supercriticalfluids in drying aerogels. For example, Kistler (J. Phys. Chem. (1932)36: 52-64) describes a simple supercritical extraction process where thegel solvent is maintained above its critical pressure and temperature,thereby reducing evaporative capillary forces and maintaining thestructural integrity of the gel network. U.S. Pat. No. 4,610,863describes an extraction process where the gel solvent is exchanged withliquid carbon dioxide and subsequently extracted at conditions wherecarbon dioxide is in a supercritical state. U.S. Pat. No. 6,670,402teaches extracting a liquid phase from a gel via rapid solvent exchangeby injecting supercritical (rather than liquid) carbon dioxide into anextractor that has been pre-heated and pre-pressurized to substantiallysupercritical conditions or above, thereby producing aerogels. U.S. Pat.No. 5,962,539 describes a process for obtaining an aerogel from apolymeric material that is in the form a sol-gel in an organic solvent,by exchanging the organic solvent for a fluid having a criticaltemperature below a temperature of polymer decomposition, andsupercritically extracting the fluid/sol-gel. U.S. Pat. No. 6,315,971discloses a process for producing gel compositions comprising: drying awet gel comprising gel solids and a drying agent to remove the dryingagent under drying conditions sufficient to reduce shrinkage of the gelduring drying. U.S. Pat. No. 5,420,168 describes a process wherebyResorcinol/Formaldehyde aerogels can be manufactured using a simple airdrying procedure. U.S. Pat. No. 5,565,142 describes drying techniques inwhich the gel surface is modified to be stronger and more hydrophobic,such that the gel framework and pores can resist collapse during ambientdrying or subcritical extraction. Other examples of extracting a liquidphase from aerogel materials can be found in U.S. Pat. Nos. 5,275,796and 5,395,805.

One preferred embodiment of extracting a liquid phase from the wet-geluses supercritical conditions of carbon dioxide, including, for example:first substantially exchanging the primary solvent present in the porenetwork of the gel with liquid carbon dioxide; and then heating the wetgel (typically in an autoclave) beyond the critical temperature ofcarbon dioxide (about 31.06° C.) and increasing the pressure of thesystem to a pressure greater than the critical pressure of carbondioxide (about 1070 psig). The pressure around the gel material can beslightly fluctuated to facilitate removal of the supercritical carbondioxide fluid from the gel. Carbon dioxide can be recirculated throughthe extraction system to facilitate the continual removal of the primarysolvent from the wet gel. Finally, the temperature and pressure areslowly returned to ambient conditions to produce a dry aerogel material.Carbon dioxide can also be pre-processed into a supercritical stateprior to being injected into an extraction chamber.

One example of an alternative method of forming an aerogel includes theacidification of basic metal oxide precursors (such as sodium silicate)in water to make a hydrogel. Salt by-products may be removed from thesilicic acid precursor by ion-exchange and/or by washing subsequentlyformed gels with water. Removing the water from the pores of the gel canbe performed via exchange with a polar organic solvent such as ethanol,methanol, or acetone. The liquid phase in the gel is then at leastpartially extracted using innovative processing and extractiontechniques.

Another example of an alternative method of forming aerogels includesreducing the damaging capillary pressure forces at the solvent/poreinterface by chemical modification of the matrix materials in their wetgel state via conversion of surface hydroxyl groups to hydrophobictrimethylsilylethers, thereby allowing for liquid phase extraction fromthe gel materials at temperatures and pressures below the critical pointof the solvent.

Large-scale production of aerogel materials or compositions can becomplicated by difficulties related to the continuous formation of gelmaterials on a large scale; as well as the difficulties related toliquid phase extraction from gel materials in large volumes usinginnovative processing and extraction techniques. Aerogel materials orcompositions of the present disclosure are preferably accommodating toproduction on a large scale. In certain embodiments, gel materials ofthe present disclosure can be produced in large scale through acontinuous casting and gelation process. In certain embodiments, aerogelmaterials or compositions of the present disclosure are produced in alarge scale which requires the use of large scale extraction vessels.Large scale extraction vessels of the present disclosure can includeextraction vessels which have a volume of about 0.1 m³ or more, about0.25 m³ or more, about 0.5 m³ or more, or about 0.75 m³ or more.

Aerogel compositions of the present disclosure can have a thickness of15 mm or less, 10 mm or less, 5 mm or less, 3 mm or less, 2 mm or less,or 1 mm or less.

The dry aerogel material or composition can be further processed tooptimize target properties of the aerogel material or composition. Incertain embodiments, dried aerogel compositions can be subjected to oneor more heat treatments, such as pyrolysis, to produce a heat treatedaerogel composition. Carefully controlled heat treatment can be used toreduce or stabilize the hydrocarbon fuel content of an aerogel materialor composition, which can improve corresponding HOC and Td properties ofthe aerogel material or composition. In certain embodiments, the heattreatment of a dried aerogel composition can take place under a range oftemperatures, pressures, durations, and atmospheric conditions.

In certain embodiments of the present disclosure, a dried aerogelcomposition can be subjected to a treatment temperature of 200° C. orabove, 250° C. or above, 300° C. or above, 350° C. or above, 400° C. orabove, 450° C. or above, 500° C. or above, 550° C. or above, 600° C. orabove, 650° C. or above, 700° C. or above, 750° C. or above, 800° C. orabove, or in a range between any two of these values.

In certain embodiments of the present disclosure, a dried aerogelcomposition can be subjected to one or more heat treatments for aduration of time of 3 hours or more, between 10 seconds and 3 hours,between 10 seconds and 2 hours, between 10 seconds and 1 hour, between10 seconds and 45 minutes, between 10 seconds and 30 minutes, between 10seconds and 15 minutes, between 10 seconds and 5 minutes, between 10seconds and 1 minute, between 1 minute and 3 hours, between 1 minute and1 hour, between 1 minute and 45 minutes, between 1 minute and 30minutes, between 1 minute and 15 minutes, between 1 minute and 5minutes, between 10 minutes and 3 hours, between 10 minutes and 1 hour,between 10 minutes and 45 minutes, between 10 minutes and 30 minutes,between 10 minutes and 15 minutes, between 30 minutes and 3 hours,between 30 minutes and 1 hour, between 30 minutes and 45 minutes,between 45 minutes and 3 hours, between 45 minutes and 90 minutes,between 45 minutes and 60 minutes, between 1 hour and 3 hours, between 1hour and 2 hours, between 1 hour and 90 minutes, or in a range betweenany two of these values.

In certain embodiments of the present disclosure, a dried aerogelcomposition can be subjected to a treatment temperature between 200° C.and 750° C. for a duration of time between 10 seconds and 3 hours.

The heat treatment of the aerogel material or composition can take placein a reduced oxygen environment. Within the context of the presentdisclosure, the term “reduced oxygen environment” refers to anatmosphere which comprises a concentration by volume of 10 vol % oxygenor less (which is below the amount of oxygen in ambient air at standardconditions). A reduced oxygen environment can comprise positivepressurized atmospheres which have elevated concentrations of inertgases, including (but not limited to) nitrogen, argon, helium, neon,argon, and xenon. A reduced oxygen environment can also comprise vacuumatmospheres which have reduced concentrations of oxygen, includingvacuums and partial vacuums. A reduced oxygen environment can furtherinclude atmospheres contained in a sealed container in which limitedcombustion has consumed a portion of the oxygen content in the sealedatmosphere. A reduced oxygen environment can comprise 10 vol % oxygen orless, 8 vol % oxygen or less, 6 vol % oxygen or less, 5 vol % oxygen orless, 4 vol % oxygen or less, 3 vol % oxygen or less, 2 vol % oxygen orless, or 1 vol % oxygen or less. A reduced oxygen environment cancomprise between 0.1 to 10 vol % oxygen, between 0.1 to 5 vol % oxygen,between 0.1 to 3 vol % oxygen, between 0.1 to 2 vol % oxygen, or between0.1 to 1 vol % oxygen. In certain embodiments of the present disclosure,a hydrophobic aerogel material or composition is heat treated in areduced oxygen atmosphere comprising between about 85% to about 99.9%inert gas (such as nitrogen). In a preferred embodiment of the presentdisclosure, a dried hydrophobic aerogel composition is heat treated in areduced oxygen atmosphere comprising between about 95% to about 99.9%inert gas (such as nitrogen) at a temperature between about 200° C. andabout 800° C. for a duration of time between about 1 minute and about 3hours.

Heat treatment of an aerogel material or composition can be highlydetrimental to various properties of certain aerogel materials. Forexample: Rao et al (J. Sol-Gel Sci. Tech., 2004, 30:141-147) teaches anaerogel material made from TEOS precursors with a variety of hydrophobicreagents (including MTMS, MTES, TMES, PhTES, ETES, DMCS, TMCS and HMDZ)added through both co-gelling and surface derivatization to providehydrophobicity, but which all lose hydrophobicity when exposed totemperatures above 310° C. (except the DMCS co-gel, which is stable upto 390° C., and the PhTES co-gel, which is stable up to 520° C.); Liu etal. (J. Sol-Gel Sci. Tech., 2012, 62:126-133) teaches an aerogelmaterial made from sodium silicate precursors which is treated with HMDZto provide hydrophobicity, but which loses its hydrophobicity whenexposed to temperatures above 430° C. in standard atmosphere; Zhou etal. (Inorg. Mat., 2008, 44-9:976-979) teaches an aerogel material madefrom TEOS precursors which is treated with TMCS to providehydrophobicity, but which loses its hydrophobicity when exposed totemperatures above 500° C. in standard atmosphere. In certainembodiments of the present disclosure, the heat treatment of the aerogelmaterial or composition of the present disclosure is limited totemperature exposures below 950° C., below 900° C., below 850° C., below800° C., below 750° C., below 700° C., below 650° C., or below 600° C.

In certain embodiments, the present disclosure provides aerogelmaterials, compositions and processing methods which allow forcontrolled heat treatment to reduce or stabilize the hydrocarbon fuelcontent of the aerogel material (thereby improving correspondingproperties of the aerogel material such as HOC and Td); and which alsoallow for the aerogel material to maintain functional levels ofhydrophobicity at high temperatures, including exposures to temperaturesof about 550° C. or more, and exposures to temperatures of about 650° C.or more.

The embodiments of the present disclosure can be practiced using any ofthe processing, extraction and treatment techniques discussed herein, aswell as other processing, extraction and treatment techniques known tothose in the art for producing aerogels, aerogel-like materials, andaerogel compositions as defined herein.

Aerogel compositions may be fiber-reinforced with various fiberreinforcement materials to achieve a more flexible, resilient andconformable composite product. The fiber reinforcement materials can beadded to the gels at any point in the gelling process to produce a wet,fibrous gel composition. The wet gel composition may then be dried toproduce a fiber-reinforced aerogel composition. Fiber reinforcementmaterials may be in the form of discrete fibers, woven materials,non-woven materials, battings, webs, mats, and felts. Fiberreinforcements can be made from organic fibrous materials, inorganicfibrous materials, or combinations thereof.

In a preferred embodiment, non-woven fiber reinforcement materials areincorporated into the aerogel composition as continuous sheet ofinterconnected or interlaced fiber reinforcement materials. The processcomprises initially producing a continuous sheet of fiber reinforced gelby casting or impregnating a gel precursor solution into a continuoussheet of interconnected or interlaced fiber reinforcement materials. Theliquid phase may then be at least partially extracted from thefiber-reinforced gel sheets to produce a sheet-like, fiber reinforcedaerogel composition.

Aerogel composition can also include an opacifier to reduce theradiative component of heat transfer. At any point prior to gelformation, opacifying compounds or precursors thereof may be dispersedinto the mixture comprising gel precursors. Examples of opacifyingcompounds include, but are not limited to: Boron Carbide [B₄C],Diatomite, Manganese ferrite, MnO, NiO, SnO, Ag₂O, Bi₂O₃, carbon black,titanium oxide, iron titanium oxide, aluminum oxide, zirconium silicate,zirconium oxide, iron (II) oxide, iron (III) oxide, manganese dioxide,iron titanium oxide (ilmenite), chromium oxide, carbides (such as SiC,TiC or WC), or mixtures thereof. Examples of opacifying compoundprecursors include, but are not limited to: TiOSO₄ or TiOCl₂.

The aerogel materials and compositions of the present disclosure havebeen shown to be highly effective as insulation materials. However,application of the methods and materials of the present disclosure arenot intended to be limited to applications related to insulation. Themethods and materials of the present disclosure can be applied to anysystem or application which would benefit from the unique combination ofproperties or procedures provided by the materials and methods of thepresent disclosure.

The following examples provide various non-limiting embodiments andproperties of the present disclosure.

Example 1

K grade sodium silicate was used as a precursor, which comprised aSiO₂:Na₂O ratio of 2.88 by wt, and contained 31.7 wt % SiO₂ and 11 wt %Na₂O. Sodium methylsiliconate was available as 30% NaSiO₃CH₃ in water.Sodium silicate and sodium methylsiliconate were combined so that 31.4%of the resulting aerogel mass originated from sodium methylsiliconate(SiO_(1.5)CH₃ from NaSiO₃CH₃), with an expected hydrophobic organiccontent of 7.0 wt % within the aerogel material.

This combination was diluted with water before adding it to 32% H₂SO₄ sothat there was 9.68 wt % silica solids (6.64 wt % SiO₂ and 3.04 wt %SiO_(1.5)CH₃) in the acidified sol. Both the H₂SO₄ and the Na₂SiO₃ werechilled to 10° C. in an ice bath. Na₂SiO₃ was added slowly to the H₂SO₄with rapid stirring. This exothermic addition was done at a rate suchthat the temperature was never above 12° C. to avoid gelation. The solwas cooled to 4° C. to encourage precipitation of some Na₂SO₄.10H₂O. Thetemperature of the solution was maintained at 4° C. To furtherprecipitate sodium sulfate, ethanol was added in an amount equivalent to68.7% of the volume of the aqueous sol, so that the molar ratio ofcomponents in the sol was 1:0.409:2.34:6.97:0.156 of Si (fromwaterglass):Si (from methyl siliconate):EtOH:H₂O:H₂SO₄. The Na₂SO₄ wasimmediately removed by vacuum filtration.

Gels were cast at target aerogel density of 0.07-0.08 g/cc by additionof dilute ammonium hydroxide (10 vol % of 28% NH₄OH in water) ascatalyst. 85 vol % sol, 5 vol % EtOH, and 10 vol % catalyst stream wereused (added over a few seconds). After the catalyst addition, the solwas stirred at 300 rpm for 30 s, then cast into a fiber reinforcingphase and allowed to gel. After curing for about 1 h, the aerogelmaterials were put in an EtOH bath with an EtOH:gel volume ratio of 3:1for 6 h to reduce the water content prior to aging. They were then agedfor 14 h at 68° C. in ethanol aging fluid containing 0.8 wt/vol % NH₃ ata fluid:gel ratio of 3:1. The coupons were subjected to solventextraction with supercritical CO₂, and then dried for 2 h at 110° C.

The fiber reinforcing phase was a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 2

Sols were made by co-hydrolyzing TEOS and MTES in EtOH and H₂O with acidcatalyst. The molar ratio of sol materials were adjusted to obtainaerogels with about 7.0 wt % organic content within the aerogelmaterial. The sol was stirred for 4 h at 60° C., then cooled to roomtemperature. There was about a 3% loss of sol volume during hydrolysis,and EtOH was added to return the sol to its original volume.

0.5M NH₄OH was added to the combined sol, with a target aerogel densityof 0.07-0.08 g/cc The sol was cast into a fiber reinforcing phase andallowed to gel. After curing for about 1 h, the aerogel materials wereaged for about 16 h at 68° C. in ethanol aging fluid containing 0.8wt/vol % NH₃ at a fluid:gel ratio of 3:1. The coupons were subjected tosolvent extraction with supercritical CO₂, and then dried for 2 h at110° C.

The fiber reinforcing phase was a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 3

Sols are made by co-hydrolyzing TEOS and MTES in EtOH and H₂O with acidcatalyst. The molar ratio of sol materials are adjusted to obtainaerogels with about 7.0 wt % organic content within the aerogelmaterial. The sol is stirred for 4 h at 60° C., then cooled to roomtemperature. Boron carbide [B₄C], carbon black, manganese dioxide,titanium oxide, or zirconium silicate are incorporated into separatebatches of the combined sol, which is then stirred for no less than 1 h.

0.5M NH₄OH is added to the combined sol, with a target aerogel densityof 0.07-0.08 g/cc The sol is cast into a fiber reinforcing phase andallowed to gel. After curing for about 1 h, the aerogel materials areaged for about 16 h at 68° C. in ethanol aging fluid containing 0.8wt/vol % NH₃ at a fluid:gel ratio of 3:1. The coupons are subjected tosolvent extraction with supercritical CO₂, and then dried for 2 h at110° C.

The fiber reinforcing phase is a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material is about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 4

Polyethylsilicate sol was produced by hydrolyzing TEOS in EtOH and H₂Owith acid catalyst, and then stirred at ambient temperature for no lessthan 6 h. Polymethylsilsesquioxane sol was produced by hydrolyzing MTESin EtOH and H₂O with acid catalyst, and then stirred at ambienttemperature for no less than 6 h. Polyethylsilicate (TEOS) andpolymethylsilsesquioxane (MTES) sols were combined in order to obtainaerogels with about 10-11 wt % organic content. Silicon carbide powder(F1200 Grit) or titanium dioxide powder were incorporated into separatebatches of the combined sol, with a weight ratio of sol-to-powder ofabout 15:1. The combined sol was stirred for no less than 1 h.

0.5M NH₄OH was added to the combined sol, with a target density of thefinal aerogels of 0.07-0.08 g/cc. The sol was cast into a non-woven,glass-fiber reinforcing phase and allowed to gel. The aerogel materialswere aged for no less than 10 h in ethanol aging fluid containing 0.5wt/vol % NH₃. The coupons were subjected to solvent extraction withsupercritical CO₂, and then dried in conventional heat at about 180° C.

The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 5

Polyethylsilicate sol is produced by hydrolyzing TEOS in EtOH and H₂Owith acid catalyst, and is then stirred at ambient temperature for noless than 6 h. Polymethylsilsesquioxane sol is produced by hydrolyzingMTES in EtOH and H₂O with acid catalyst, and is then stirred at ambienttemperature for no less than 6 h. Polyethylsilicate (TEOS) andpolymethylsilsesquioxane (MTES) sols are combined in order to obtainaerogels with about 10-11 wt % organic content. Iron oxide, titaniumcarbide, diatomite, manganese ferrite or iron titanium oxide areincorporated into separate batches of the combined sol. The combined solis stirred for no less than 1 h.

0.5M NH₄OH is added to the combined sol, with a target density of thefinal aerogels of 0.07-0.08 g/cc. The sol is cast into a non-woven,glass-fiber reinforcing phase and allowed to gel. The aerogel materialsare aged for no less than 10 h in ethanol aging fluid containing 0.5wt/vol % NH₃. The coupons are subjected to solvent extraction withsupercritical CO₂, and then dried in conventional heat at about 180° C.

The resulting aerogel material are about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 6

Sols were made by co-hydrolyzing TEOS and an organosilane hydrophobe, inEtOH and 1 mM aq oxalic acid. The organosilane hydrophobe coprecursorscould be chosen from the following: methyl trimethoxysilane (MTMS),methyl triethoxysilane (MTES), trimethyl ethoxysilane (TMES), ethyltriethoxysilane (ETES), and phenyl triethoxysilane (PhTES). In thisexample, PhTES was used as the organosilane hydrophobe. The molar ratioof EtOH:H₂O:oxalic acid was kept constant at 5:7:1.26×10⁻⁴, with theoxalic acid introduced together with the water as 1 mM oxalic acid. Amolar ratio of TEOS and PhTES was provided in order to obtain aerogelswith 8.0 and 9.0 wt % hydrophobic organic content in each case, and thetarget density was 0.07-0.08 g/cc. The molar ratios of sol componentsfor these two formulations were 0.0719:1:8.98:12.57:2.26×10⁻⁴ and0.0825:1:9.18:12.85:2.31×10⁻⁴ PhTES:TEOS:EtOH:H₂O:oxalic acid,respectively.

The sols were stirred for 15 min, then cast into a fiber reinforcingphase, and allowed to gel in an oven at 60° C. After curing for 21-33 hat 60° C., the aerogel materials were aged for 22 h at 68° C. in ethanolaging fluid containing 0.8 wt/vol % NH₃ at a fluid:gel ratio of 3:1. Thecoupons were subjected to solvent extraction with supercritical CO₂, andthen dried for 2 h at 110° C.

The fiber reinforcing phase was a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 7

Sols were made by co-hydrolyzing TEOS and PhTES in MeOH with 1 mM aqoxalic acid catalyst. The molar ratio of MeOH:H₂O:oxalic acid was keptconstant at 66:7:1.26×10⁻⁴, with the oxalic acid introduced togetherwith the water as 1 mM oxalic acid. The target density was 0.07-0.08g/cc for all formulations. The PhTES content was varied to achieveaerogels with 7.0, 11.0, or 19.0 wt % target organic content. The molarratios of sol components for these formulations were1:0.062:16.57:1.76:3.16×10⁻⁵, 1:0.105:18.15:1.93:3.47×10⁻⁵, and1:0.217:22.18:2.35:4.24×10⁻⁵ TEOS:PhTES:MeOH:H₂O:oxalic acid,respectively. The sols were stirred for 24 h at 28° C.

To gel the hydrolyzed sols, 1 M NH₄OH was added in an amount that addsan additional 1 mol of H₂O for every mol of H₂O in the previous step.This contributes 0.0316, 0.0347, or 0.0424 mol NH₄OH per mol of TEOS forthe 7.0, 11.0, and 19.0 wt % organics formulations, respectively. Thesols were stirred for 3 min, then cast into a fiber reinforcing phase,and allowed to gel at 28° C. The gels were cured at room temperature for2 days, then soaked in an ethanol bath for 4 days with fresh ethanolevery 24 h. The coupons were subjected to solvent extraction withsupercritical CO₂, and then dried for 2 h at 110° C.

The fiber reinforcing phase was a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 8

Sols were made by co-hydrolyzing tetramethylorthosilicate (TMOS) andPhTES in MeOH with 86 mM NH₄OH catalyst. The molar ratio between thesolvents and catalyst was kept constant at 11:5:3.7×10⁻³ MeOH:H₂O:NH₄OH,with the NH₄OH introduced together with the water as 86 mM NH₄OH. Thetarget density was 0.07-0.08 g/cc for all formulations. The PhTEScontent was varied to achieve aerogels with 7.0, 11.0, or 19.0 wt %target organic content. The molar ratios of sol components for theseformulations were 1:0.062:16.61:7.55:5.59×10⁻³,1:0.105:18.04:8.20:6.07×10⁻³, and 1:0.217:21.78:9.90:7.33×10⁻³TMOS:PhTES:MeOH:H₂O:NH₄OH, respectively.

The sols were stirred for 15 min, then cast into a fiber reinforcingphase, and allowed to gel. The gels were cured at room temperature for 3days, then soaked in an ethanol bath for 4 days with fresh ethanol every24 h. The coupons were subjected to solvent extraction withsupercritical CO₂, and then dried for 2 h at 110° C.

The fiber reinforcing phase was a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 9

Sols were made by co-hydrolyzing TEOS and 1,2-bis(triethoxysilyl)ethane(BTESE) in EtOH and H₂O with 1M HCl catalyst. Aerogels with 7.0, 8.0, or9.0 wt % organic content were obtained by using TEOS:BTESE:EtOH:H₂O:HClmolar ratios of 1:0.223:13.84:3.46:2.42×10⁻³,1:0.275:15.04:3.76:2.63×10⁻³, and 1:0.334:16.24:4.06:2.84×10⁻³,respectively. In each case, the ratio between the solvents and catalystwas kept constant at 8:2:1.4×10⁻³ EtOH:H₂O:HCl while the BTESE contentwas varied. The sol was stirred for 4 h at 60° C., then cooled to roomtemperature. There was about a 3% loss of sol volume during hydrolysis,and EtOH was added to return the sol to its original volume.

To gel the hydrolyzed sol, diluted NH₄OH was added so that the finalcasted sol contained 8.0 vol % 0.5 M NH₄OH, and the target density ofthe final aerogels was 0.07-0.08 g/cc. The sol was cast into a fiberreinforcing phase and allowed to gel. After curing for about 1 h, theaerogel materials were aged for about 16 h at 68° C. in ethanol agingfluid containing 0.8 wt/vol % NH₃ at a fluid:gel ratio of 3:1. Thecoupons were subjected to solvent extraction with supercritical CO₂, andthen dried for 2 h at 110° C.

The fiber reinforcing phase was a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material was about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 10

K grade sodium silicate is used as a precursor, which comprises aSiO₂:Na₂O ratio of 2.88 by wt, and contains 31.7 wt % SiO₂ and 11 wt %Na₂O. The sodium silicate precursor is first diluted with water, thenadded to 32% H₂SO₄. The resulting solution comprises 10.34 wt % SiO₂,1.34 M Na⁺, and 1.50 M H⁺ in the acidified sol. Both the H₂SO₄ and theNa₂SiO₃ are chilled to 10° C. in an ice bath, then the Na₂SiO₃ is addedslowly to the H₂SO₄ solution with rapid stirring. This exothermicaddition is done at a rate such that the temperature is never above 12°C. to avoid gelation. The sol is cooled to 4° C. to encourageprecipitation of some Na₂SO₄.10H₂O. The temperature of the solution ismaintained at 4° C.

THF is added in an amount until 6.72 wt % SiO₂ is in the final sol,thereby further precipitating Na₂SO₄. The precipitated Na₂SO₄ isimmediately removed by vacuum filtration, and NaCl is added to thefiltered sol solution until the sol is saturated. The NaCl inducesseparation of an aqueous and an organic phase. 95% of the H₂O is removedfrom the organic phase, and 100% of the SiO₂ is partitioned into theorganic phase. The organic phase is isolated, with an expected solidcontent of about 0.18 g SiO₂/mL. Ethanol is added in an amountequivalent to 104% of the volume of the THF layer, such that the molarratio of components in the sol is1(Si):6.256(EtOH):0.975(H₂O):4.115(THF).

An MTES precursor sol solution is prepared, comprising: 69.4 wt % MTESwith 2.7H₂O:Si (mole ratio) and 70 mM acetic acid (99.7%) diluted withEtOH, which provides an expected 26 wt % solid content [SiO_(1.5)(CH₃)].The molar ratio of MTES:EtOH:H₂O:HOAc is 1:0.624:2.703:0.0199. The solis stirred for 5 h in a thermos, then quenched by chilling.

85.9 vol % silicic acid sol (1a) and 14.1 vol % MTES sol (1b) arecombined and stirred for 2 h, with an expected 31.4 wt % of the finalaerogel mass originating from the hydrophobic component (SiO_(1.5)CH₃from MTES), and an expected hydrophobic organic content of 7.0 wt %.

Gels are cast at a target aerogel density of 0.07-0.08 g/cc by additionof EtOH and dilute ammonium hydroxide (2.5 vol % of 28% NH₄OH in water)as catalyst. 67 vol % sol solution, 21 vol % EtOH, and 12 vol % catalyststream are used (added over a few seconds). After catalyst addition, thesol is stirred at 300 rpm for 30 s, then cast into a fiber reinforcingphase and allowed to gel. After curing for about 1 h, the aerogelmaterials are aged for about 16 h at 68° C. in ethanol aging fluidcontaining 0.8 wt/vol % NH₃ at a fluid:gel ratio of 3:1. The coupons aresubjected to solvent extraction with supercritical CO₂, and then driedfor 2 h at 110° C.

The fiber reinforcing phase is a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material is about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density).

Example 11

K grade sodium silicate is used, which has 2.88 SiO₂:Na₂O by wt,contains 31.7 Wt % SiO₂ and 11 wt % Na₂O, and has a density of 1.48g/mL. It is first diluted with water so that the diluted solutioncontains 22.1 wt % original waterglass (7.0 wt % SiO₂). The dilutesodium silicate is ion exchanged by passing it through amberlite Na⁺resin. The resulting silicic acid is then gelled by addition of H₂O and1 M NH₄OH catalyst so that the diluent H₂O and the catalyst streamconstitute 6.9 vol % and 0.4 vol %, respectively, of the final hydrosol.The sol is stirred at 300 rpm for 30 seconds prior to casting into afiber reinforcing phase and gelation. The molar ratio of Si:H₂O:NH₃ is1:47.8:0.0016 and the targeted silica aerogel density is 0.07-0.08 g/cc.The gels are aged at 50° C. for 3 h. Solvent exchange with ethanol iscarried out three times in 36 h, then the ethanol is exchanged withhexane three times in 36 h.

The fiber reinforcing phase is a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material is about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 aerogel density, not including the hydrophobictreatment).

Hydrophobic treatment of the wet gel is done with one of the followinghydrophobic silylating agents: methyltrimethoxysilane (MTMS),methyltriethoxysilane (MTES), vinyltrimethoxysilane (VTMS),phenyltrimethoxysilane (PhTMS), phenyltriethoxysilane (PhTES), ordimethyldimethoxysilane (DMDMS). Silanization of the gels is carried outin a hexane bath containing 20 vol % hydrophobe at 50° C. for 24 h usinga 4:1 fluid:gel ratio. The molar ratio of the hydrophobe in the fluid toSi in the gel ranges from 2.8-5.0 depending on which hydrophobe is used.The gels are washed with hexane two times in 24 h, then subjected tosolvent extraction with supercritical CO₂, and then dried for 2 h at110° C.

Example 12

Silica gel is prepared by the hydrolysis and condensation of TEOS,diluted in EtOH, in the presence of oxalic acid catalyst. The molarratio of TEOS:EtOH:H₂O:oxalic acid is 1:7.60:10.64:1.92×10⁴, with theoxalic acid introduced together with the water as 1 mM oxalic acid. Thetargeted silica aerogel density is 0.07-0.08 g/cc. The sol is stirredfor 15 min, then cast into a fiber reinforcing phase, and allowed to gelin a 60° C. oven.

The fiber reinforcing phase is a silica PD batting with 9-microndiameter fibers, about 10 mm thick with a density of about 3.8 oz/sq ft.The resulting aerogel material is about 45 wt % aerogel and 55 wt %fiber, resulting in an expected material density of about 0.16-0.20 g/cc(given a 0.07-0.08 g/cc aerogel density, not including the hydrophobictreatment).

The gel is transferred to a bath containing 20 vol % of a hydrophobicreagent in methanol and heated at 45° C. for 24 h using at 4:1 fluid:gelratio. The hydrophobic reagent is one of the following:methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES),ethyltriethoxysilane (ETES), or phenyltriethoxysilane (PhTES). The molarratio of the hydrophobe in the fluid to Si in the gel ranges from2.8-4.8 depending on which hydrophobe is used. The gels are then washedwith EtOH three times, 6 h each time, at 45° C., then subjected tosolvent extraction with supercritical CO₂, and then dried for 2 h at110° C.

Example 13

Examples 1, 2, 6, 7, 8, and 9 produced aerogel compositions with about7.0-9.0 wt % hydrophobic organic content in the aerogel material(3.0-5.0 wt % of the composite) expected in each example. Example 4produced aerogel compositions with about 9.0-11.0 wt % hydrophobicorganic content in the aerogel material (4.0-6.0 wt % of the composite).Examples 7 and 8 also produced aerogel compositions with about 11.0 wt %and 19.0 wt % PhTES hydrophobic organic content in the aerogel material(6.0-9.0 wt % of the composite). Examples 3 and 5 can produce aerogelcompositions with about 9.0-11.0 wt % hydrophobic organic content in theaerogel material under adjusted production conditions (amount ofhydrophobic material, time, temp, etc). Examples 10-12 can produceaerogel compositions with about 7.0-9.0 wt % hydrophobic organic contentin the aerogel material under adjusted production conditions (amount ofhydrophobic material, time, temp, etc).

Samples produced in Examples 1, 2, 6, 7, 8, and 9, as well as samplesproduced in Example 4 which comprise silicon carbide powder, weresubjected to heat treatment in a tube furnace under N₂, with atemperature ramp rate of 10° C./min until a selection of treatmenttemperatures ranging between 200° C. and 700° C. were reached. After atreatment duration period was complete, the furnace was allowed to coolat a cooling ramp of 5° C./min, and the samples were removed.

The treated samples included: 7% MTES samples from Example 2; 7%NaSiO₃CH₃ samples from Example 1; 7%, 8% and 9% BTESE samples fromExample 9; 8% and 9% PhTES samples from Example 6; 7%, 11% and 19% PhTESsamples from Example 7; and 7%, 11% and 19% PhTES samples from Example8. Samples were subjected to heat treatment under various temperaturesranging between 200° C. and 700° C., for durations of time rangingbetween 10 seconds and 1 hours. Samples treated at 475° C. for 10minutes and 525° C. for 10 minutes were selected for further testing.

Samples produced in Example 4 which comprise titanium dioxide powderwere subjected to heat treatment by sealing sample coupons from eachbatch in stainless steel foil bags and inserting the bags into apreheated inert furnace at various temperatures between 450° C. and 800°C. for a period of no greater than 60 minutes.

Treated samples from Example 4 (titanium dioxide powder or siliconcarbide powder) are identified in the present disclosure by the powdermaterial (S=Silicon carbide; T=titanium dioxide), by the heat treatmenttemperature (450-800) and by the treatment time (0-60).

Heat treatment of samples from 7%, 8% and 9% BTESE showed signs ofdecomposition starting at about 475° C. Heat treatment of samples fromPhTES all showed signs of unstable phenyl species at high temperaturesabove 400° C.

Example 14

Table 1 presents density measurements for treated aerogel compositesamples from Example 13. Density measurements were completed accordingto ASTM C₁₆₇. All composite aerogel samples had measured densities below0.216 g/cc.

Example 15

Table 1 presents thermal conductivity (TC) measurements for treatedaerogel composite samples from Example 13. TC measurements werecompleted according to ASTM C177 at a temperature of about 37.5° C. anda compression of 2 psi (8×8 samples) or 8 psi (4×4 samples).

All treated aerogel composite samples had thermal conductivitymeasurements at or below 31.6 mW/mK.

Example 16

An aerogel composition with about 7.0-8.0 wt % hydrophobic organiccontent is typically expected to be hydrophilic as produced, with anexpected C1511 water uptake value (under 15 minute submersion in ambientconditions) of about 350 wt % or higher.

Table 1 presents liquid water uptake measurements for treated aerogelcomposite samples from Example 13, both before and after reduced oxygenheat treatment. All measurements were made according ASTM C1511 (under15 minute submersion in ambient conditions).

Pre-treatment samples for 7% MTES and 7% NaSiO₃CH₃ both had liquid wateruptake measurements above 400 wt % water uptake. Pre-treatment samplesfor 7%, 8% and 9% BTESE all had liquid water uptake measurements above340 wt % water uptake. Pre-treatment samples for PhTES materials all hadliquid water uptake measurements above 280%.

Post-treatment samples for 7% MTES had liquid water uptake measurementsof about 0.0 wt % water uptake, which is lower than pre-treatmentsamples for 7% MTES. Post-treatment samples for 7% NaSiO₃CH₃ had liquidwater uptake measurements of about 81 wt % water uptake (for samplesheat treated at 475° C. for 10 min). All post-treatment samples forBTESE had liquid water uptake measurements above 290 wt % water uptake.All post-treatment samples for PhTES had liquid water uptakemeasurements above 275 wt % water uptake.

Example 17

Table 1 presents heat of combustion (HOC) measurements for treatedaerogel composite samples from Example 13, both before and after reducedoxygen heat treatment. HOC measurements were completed according toconditions comparable to ISO 1716 measurement standards.

Pre-treatment samples for 7% MTES had HOC measurements of about 600cal/g; post-treatment samples (heat treated at 525° C. for 10 min) hadHOC measurements of about 425 cal/g. Pre-treatment samples for 7%NaSiO₃CH₃ had HOC measurements of about 415 cal/g; post-treatmentsamples (heat treated at 525° C. for 10 min) had HOC measurements ofabout 140 cal/g. Pre-treatment samples for 9% BTESE had HOC measurementsof about 780 cal/g; post-treatment samples for 9% BTESE (heat treated at525° C. for 10 min) had HOC measurements of about 285 cal/g.Pre-treatment samples for 9% PhTES (from Example 3-1) had HOCmeasurements of about 437 cal/g; post-treatment samples (heat treated at525° C. for 10 min) had HOC measurements of about 144 cal/g.Pre-treatment samples for 7% PhTES (from Example 3-3) had HOCmeasurements of about 351 cal/g; post-treatment samples (heat treated at400° C. for 10 min) had HOC measurements of about 120 cal/g.Pre-treatment samples for 11% PhTES (from Example 3-3) had HOCmeasurements of about 403 cal/g; post-treatment samples (heat treated at400° C. for 10 min) had HOC measurements of about 110 cal/g.

Example 18

FIG. 1 shows CP/MAS ²⁹Si Solid State NMR analysis for 7% MTES samplesfrom Example 13, both before and after reduced oxygen heat treatment at525° C. for 10 minutes.

Pre-treatment samples for 7% MTES showed T¹⁻²:T³ ratios of about 0.463,and Q²⁻³:Q⁴ ratios of about 1.961. Post-treatment samples for 7% MTESshowed T¹⁻²:T³ ratios of about 0.272, and Q²⁻³:Q⁴ ratios of about 0.842.Overlapping peaks were deconvoluted an integrated individually to obtainratios.

Example 19

FIG. 2 shows TGA/DSC analysis for 7% MTES samples, 7% NaSiO₃CH₃ samples,9% BTESE samples, and 9% PhTES (Example 3-1) samples from Example 13,both before and after reduced oxygen heat treatment at 525° C. for 10minutes. TGA/DSC analysis was completed for temperatures ranging fromambient temperature up to 1000° C., with a ramp rate of 20° C./min.

Table 1 presents the onset of thermal decomposition temperatures (° C.)for the post-treatment samples, based on the TGA/DSC analysis plotsshown in FIG. 2.

Post-treatment samples for 7% MTES (heat treated at 525° C. for 10 min)had Td measurements of about 545° C. Post-treatment samples for 7%NaSiO₃CH₃ (heat treated at 525° C. for 10 min) had Td measurements ofabout 600° C. Post-treatment samples for 9% BTESE (heat treated at 525°C. for 10 min) had Td measurements of about 460° C. Post-treatmentsamples for 9% PhTES (heat treated at 525° C. for 10 min) had Tdmeasurements of about 595° C.

TABLE 1 Composite Thermal Liquid Water Liquid Water DensityConductivity** Uptake* Uptake** HOC* HOC** Td** Example (g/cc) (mW/M-K)(wt %) (wt %) (cal/g) (cal/g) (° C.) 1 0.173 30.5 ~450 81.0 416 142 6002 0.159 25.1 ~425 0.0 601 426 544 4-T-5-600 0.206 15.9 — 5.8 — 269 6364-T-10-600 ~0.200 — — 0.9 — — 626 4-T-5-625 0.187 15.8 — 4.5 — 317 6244-T-10-625 ~0.185 — — 1.7 — — 625 4-T-5-650 0.203  16.85 — 1.5 — 265 6364-T-20-650 ~0.200 — — 1.5 — — 625 4-S-10-525 0.202 16.0 — 2.5 — 355 6094-S-10-550 0.216 18.0 — 0.0 — 316 610 4-S-10-575 0.212 — — 0.0 — 343 6256-8% 0.142 — 475 401.0 252 — — 6-9% 0.148 21.0 480 432.0 437 144 5947-7% 0.185 20.3 450 360.0 715 146 — 7-11% 0.182 24.9 371 311.0 868 352 —7-19% 0.199 31.2 283 277.0 1076  571 — 8-7% 0.180 17.9 403 354.0 351 132— 8-11% 0.177 17.5 412 413.0 403 157 — 8-19% 0.175 18.7 461 404.0 531303 — 9-7% 0.182 — ~400 343.0 612 — — 9-8% 0.180 — ~355 328.0 — — — 9-9%0.183 31.6 ~345 297.0 780 287 459 *Before reduced oxygen heat treatment**After reduced oxygen heat treatment at 475° C.-525° C. for 10 min,unless otherwise indicated — No measurement taken

As used herein, the conjunction “and” is intended to be inclusive andthe conjunction “or” ˜ is not intended to be exclusive unless otherwiseindicated. For example, the phrase “or, alternatively” is intended to beexclusive.

The use of the terms “a”, “an”, “the”, or similar referents in thecontext of describing the disclosure (especially in the context of theclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.

The terms “comprising,” “having,” “including,” and “containing” are tobe construed as open-ended terms (i.e., meaning “including, but notlimited to,”) unless otherwise noted.

As used herein, the term “about” refers to a degree of deviation typicalfor a particular property, composition, amount, value or parameter asidentified; such as deviations based on experimental errors, measurementerrors, approximation errors, calculation errors, standard deviationsfrom a mean value, routine minor adjustments, and so forth.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,“such as”, “for example”) provided herein, is intended merely to betterilluminate the disclosure and does not pose a limitation on the scope ofthe disclosure unless otherwise claimed.

What is claimed is:
 1. A reinforced hydrophobic aerogel composition comprising a silica-based framework, the silica-based framework comprising hydrophobic bound silicon; wherein the reinforced hydrophobic aerogel composition has the following properties: i) liquid water uptake of 40 wt % or less; and ii) heat of combustion of less than 717 cal/g.
 2. The reinforced hydrophobic aerogel composition of claim 1, further comprising a fiber reinforcement material or a sheet of the fiber reinforcement material.
 3. The reinforced hydrophobic aerogel composition of claim 1, further comprising a reinforcement material that is non-fibrous.
 4. The reinforced hydrophobic aerogel composition of claim 1, further comprising a foam reinforcement material.
 5. The reinforced hydrophobic aerogel composition of claim 1, wherein the reinforced hydrophobic aerogel composition has a heat of combustion of from 250 cal/g to 717 cal/g.
 6. The reinforced hydrophobic aerogel composition of claim 5, wherein the reinforced hydrophobic aerogel composition has a heat of combustion of from 460 cal/g to 717 cal/g.
 7. The reinforced hydrophobic aerogel composition of claim 5, wherein the reinforced hydrophobic aerogel composition has a heat of combustion of from 600 cal/g to 717 cal/g.
 8. The reinforced hydrophobic aerogel composition of claim 1, wherein the reinforced hydrophobic aerogel composition has a thermal conductivity of 40 mW/M*K or less.
 9. The reinforced hydrophobic aerogel composition of claim 8, wherein the reinforced hydrophobic aerogel composition has a thermal conductivity from 5 mW/M*K to 40 mW/M*K.
 10. The reinforced hydrophobic aerogel composition of claim 1, wherein the reinforced hydrophobic aerogel composition has a density from 0.40 g/cm3 or less.
 11. The reinforced hydrophobic aerogel composition of claim 1, further comprising hydrophobic organic material.
 12. The reinforced hydrophobic aerogel composition of claim 11, wherein the hydrophobic organic material has an onset of thermal decomposition from 300° C. to 700° C.
 13. The reinforced hydrophobic aerogel composition of claim 11, wherein the hydrophobic organic material has an onset of thermal decomposition from 350° C. to 700° C.
 14. The reinforced hydrophobic aerogel composition of claim 11, wherein the hydrophobic organic material has an onset of thermal decomposition from 450° C. to 700° C.
 15. The reinforced hydrophobic aerogel composition of claim 11, wherein the hydrophobic organic material has an onset of thermal decomposition from 515° C. to 700° C.
 16. The reinforced hydrophobic aerogel composition of claim 11, wherein a content of the hydrophobic organic material in the reinforced hydrophobic aerogel composition is from 2 wt % to 15 wt %.
 17. The reinforced hydrophobic aerogel composition of claim 1, wherein the reinforced hydrophobic aerogel composition has a ratio of T¹⁻²:T³ of between about 0.01 and 0.4, and a ratio of Q²⁻³:Q⁴ of between about 0.1 and 1.5.
 18. A hydrophobic aerogel composition comprising a silica-based framework, hydrophobic organic material, and a reinforcement material, wherein the hydrophobic aerogel composition has the following properties: heat of combustion of less than 717 cal/g; and hydrophobic organic material content is from 2 wt % to 15 wt %.
 19. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic aerogel composition has a heat of combustion from 460 cal/g to 717 cal/g.
 20. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic aerogel composition has a heat of combustion from 600 cal/g to 717 cal/g.
 21. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic organic material has an onset of thermal decomposition from 300° C. to 700° C.
 22. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic organic material has an onset of thermal decomposition of from 350° C. to 700° C.
 23. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic organic material has an onset of thermal decomposition of from 450° C. to 700° C.
 24. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic organic material has an onset of thermal decomposition of from 515° C. to 700° C.
 25. The hydrophobic aerogel composition of claim 18, wherein the hydrophobic aerogel composition has a thermal conductivity is 40 mW/M*K or less.
 26. A reinforced hydrophobic aerogel composition comprising a silica-based framework, the silica-based framework comprising hydrophobic bound silicon; wherein the reinforced hydrophobic aerogel composition has the following properties: i) liquid water uptake of 40 wt % or less; and ii) heat of combustion of less than 750 cal/g.
 27. The reinforced hydrophobic aerogel composition of claim 26, further comprising hydrophobic organic material.
 28. The reinforced hydrophobic aerogel composition of claim 27, wherein the hydrophobic organic material has an onset of thermal decomposition of from 300° C. to 700° C.
 29. The reinforced hydrophobic aerogel composition of claim 28, wherein a content of the hydrophobic organic material in the reinforced hydrophobic aerogel composition is from 2 wt % to 15 wt %.
 30. The reinforced hydrophobic aerogel composition of claim 27, wherein the hydrophobic organic material has an onset of thermal decomposition of from 350° C. to 700° C.
 31. The reinforced hydrophobic aerogel composition of claim 26, wherein the heat of combustion from 460 cal/g to 717 cal/g.
 32. The reinforced hydrophobic aerogel composition of claim 26, wherein the reinforced hydrophobic aerogel composition has a thermal conductivity is 40 mW/M*K or less. 